‘Oh, I’m a bumper!” says Kathy Bates as I reach out to shake her hand. A small fist comes towards me with a large, round, pink-rose ring on the middle finger. We bump and laugh and one of the truly unique American acting powerhouses of the past half-century beams back at me. She has a splendid smile, full of mischief and wisdom: a small and compact woman buoyed by that straight-up, unfeigned southern warmth that abides no matter where you encounter it. She fusses over me kindly, offering drinks – a world away from the nervous, shy, deeply rattled and easily hurt woman I have just watched in Clint Eastwood’s new movie, Richard Jewell.

Bates plays Bobi, the mother of the eponymous character, a security guard at the 1996 Olympics in Centennial Park, Atlanta, who discovered a backpack full of pipe-bombs, laid by white-supremacist terrorist Eric Rudolph, minutes before it exploded. Although one person died and 111 were injured, Jewell saved countless lives by clearing the area before the bombs exploded. But within days he found himself under a nationwide spotlight as the FBI focused on him as their chief suspect.

For 88 days, he and his mother endured a press siege outside their shared apartment – and a vicious feeding-frenzy in the national media – until the FBI halfheartedly admitted he hadn’t planted the bomb. Almost a decade later, Rudolph confessed in a plea bargain to avoid the death penalty. Jewell enjoyed only a brief vindication though, dying of heart failure aged 44 in 2007.

Bates with Sam Rockwell and Paul Walter Hauser in Richard Jewell. Photograph: Claire Folger/AP

Eastwood’s movie is about enormous pressure being brought to bear on people unable to handle it, and Bates and Paul Walter Hauser do sterling work to delineate the suffering the pair underwent. Hauser is a good-natured fool, a fantasist deluded about his security-guard role, claiming he is “law-enforcement” even as the FBI laugh in his face. Bates’ Bobi is all nerves and near-hysteria, absorbing every blow like a woman on the verge of collapse. But her final speech, the true emotional climax of the movie, burns with a righteous fury, even as the tears fill her eyes. Eastwood needed an actor of commanding stature to deliver weakness, then rage, then fragile strength, and Bates has deservedly earned the lion’s share of the movie’s acclaim.

On Monday, it earned her a fourth Oscar nomination; today she is pleased, and nostalgic for her first one, for Misery, back in 1991, which translated into a win. “I arrived home two days before the ceremony. Literally only had enough time to put on the dress. Thank God it fit. The night was a dream come true. My fiance was worried I would lose, but when Daniel Day-Lewis had the envelope in his hands, in my mind I saw my name in it. Heard him say it. Sailed up the steps and forgot to thank my fiance and my mother, who deserved all my thanks sitting at home.

“This time is different,” she says, “because Richard Jewell is based on a true story. All we wanted was for Bobi Jewell to feel the film vindicated her son. I wanted her to like my portrayal of her. She’s waited 23 years for justice. I’ve never felt quite like this before. Whatever happens now, I’m just grateful the film will get more eyeballs.”

Bates’ voice breaks and her breathing shortens when she speaks about the woman she plays, and with whom she made contact long before shooting started. “It was my birthday the day we met. She baked me a pound cake. She had the Vanity Fair article the movie is based on, and the script, which she’d annotated with things like: ‘I’d never do this, I’d never call him that.’ She was very meticulous. It was obvious she’s still absolutely raw from this, even 25 years later. It still affects her, and it’s never going to change.”

Everybody loves Bates, but the movie – with its Trumpish overtones – has not escaped criticism. The enemies are the media and the “deep state”. The guy who gets off scot-free is Rudolph – I tell Bates that particularly disappointed me – and she seems to partly agree: “Rudolph was just evil, obviously.”

She also appears sympathetic to disquiet over Olivia Wilde’s character, Kathy Scruggs, the journalist who put Jewell in the headlines in the most negative way – and is the most venomous portrayal of a woman in an Eastwood movie for many years. Scruggs died of a drug overdose aged 42, which means she can’t defend herself against the film’s claim that she slept with an FBI agent (Jon Hamm) for the scoop.

In my day, if you went up to a guy’s room, you knew why you were going and it was consensual

“I was a little uncomfortable with her character,” says Bates, “though I think Bobi sort of balances that out in the movie.” She and Wilde didn’t share any scenes, “which was frustrating, because she’s Irish and I’m Irish, and I think Irish people make the best actors.” Bates looks for the positive. “I loved Booksmart [Wilde’s directorial debut]. She’s a brilliant director – and that counts for a lot.”

This season, Bates has also admired Joker, Jojo Rabbit (“unique, heart-rending and so relevant – as is Parasite”) and Little Women. “It was absolutely delightful in every way. I adored it. I’m sick Greta Gerwig didn’t get a directing nomination. Her adaptation was incredible, but her vision as a director is on that screen in every word and moment of those performances.”

She has also been trading larky congratulations – and commiserations – with Uncut Gems star Adam Sandler, who played her son in The Waterboy. “You was robbed!! But Mama loves you!!! … You da GOAT!!” she told him on Twitter. She expands, a touch more soberly: “Adam is a kind and gentle man. Friends and family are very important to him. He’s in this business, but not of it, if you get my drift.”

Still, Bates’ admiration for Eastwood beats all. “I remember telling him on the set: ‘I’ve been in this business half a century but working with you, I feel like I’ve hit the big time!’”

Bates in Misery, 1991. Photograph: Allstar/COLUMBIA

In truth, she hit that some time back. Bates made her movie debut in 1971, in Milos Forman’s Taking Off, as a singer in a crowd scene, for which she was paid $50. Her next screen role wasn’t for another seven years, but she established herself as an exciting new presence in landmark stage productions which, when they were adapted for cinema, routinely traded her for other actors: Michelle Pfeiffer, Sissy Spacek, Diane Keaton.

She also received a barrage of sexist and appearance-based criticism from male critics, particularly the late Playbill critic John Simon, whose most benevolent remarks included that she was “enormously overweight” and “unattractive”. She remembers a particularly brutal British press conference for “a bad movie I was in” – probably 1991’s At Play in the Fields of the Lord.

“One guy was so nasty that I went up to my room and I cried like a kid out of kindergarten. Our producer came in and said: ‘Kid, you’ve gotta get tough.’ And in the middle of everything I got on a plane and I went home. It was so cruel, so unnecessarily cruel.”

Bates is circumspect in hindsight. “The thing is, you remember those moments for ever,” she says. “Even if you don’t remember the exact words, it’s a dart through the heart. But as Harold Clurman said – something it took me a long time to accept – ‘You’ve gotta have the manure, you’ve got to take all the shit to really grow.’”

I remind her that when she was 41 and promoting Misery, she said: “A woman, a character actress, in her 40s – I’ll be very interested to see how Hollywood treats us over the next 10 or 15 years.”

“Wow,” she says, 29 years later, “I said that? Holy crap. I didn’t know I was such a smart cookie back then! It was my first big movie and I was stunned by the press. The very first question I got asked at a round table was: ‘You’re not Michelle Pfeiffer.’ And I was like: ‘No, I’m not!’” Her face collapses into incredulity. “I was still very serious about things back then.”

Bates in Titanic with Leonardo DiCaprio and Kate Winslet. Photograph: Allstar/20 CENTURY FOX/Sportsphoto Ltd.

Bates’ position as a female actor who has long dealt with many of the issues in play, post #MeToo, gives her an unusual – and sometimes difficult – insight into how the industry has, and has not, evolved.

“About people like Weinstein and the casting couch and all of that,” she says, “I have a confession. In my day, if you went up to a guy’s hotel room, you knew exactly why you were going and in those days it was consensual. Times were different, but I really support the women who are coming forward now and I’m not happy about the men who are being accused falsely – but the ones who deserve all they’re getting, my feeling is hey, go for it.”

That she wasn’t a classic starlet didn’t insulate her from misogyny’s pigeonholing – right? “I hate to complain about it, but never being considered the romantic lead – which is fine, I’m over that, been there, done that – means they look at me in a different way. But then I look at my friends who are beautiful girls but not working after 40 – very few of them. Well, Nicole Kidman is …

“But I’m so grateful that television is providing all these great roles for us, with people like Ryan Murphy around [the producer of American Horror Story, which has cast Bates several seasons running] we’ve been given a second life. I give Ryan a lot of credit. That show’s like being in a repertory company. Oh yes, horror has been veeeery good to me!” She chuckles like a fiend.

Her movie career took off after Misery, in which she imbued her Nurse Ratched-meets-Medea character with a surprising degree of sweetness and vulnerability. So memorable – and lauded – was her performance, people have tended to conflate her with her character Annie Wilkes, even as she was busy building a gallery of richly detailed, multifarious and moving other performances, including the warm-hearted “new money” Molly Brown in 1997’s Titanic. She puts the film’s enduring appeal down to the wealth inequality at its centre: “The murder of the third-class passengers being locked below decks revealed the brutality of class struggles around the globe.” That, too, is perhaps why raft-gate persists as a debate: “We all wanted Jack to survive, and there did seem to be enough room for him to squeeze on.”

Kathy Bates in About Schmidt. Photograph: Claudette Barius/AFP/Getty Images

Five years later, another indelible turn: opposite Jack Nicholson in Alexander Payne’s About Schmidt. A nude hot-tub scene went a long way to shake off the memory of Misery. “I think a lot of women in that audience were thrilled to see a real woman up there on the screen in all her glory,” she said at the time. Stripped of its nudity context, I suggest, that almost sounds like a proud rallying cry for the kinds of characters she takes on.

“It does, doesn’t it?” she nods. “And if I’m proud of anything, it’s leaving behind me such a wide range of interesting, real women.”

Not that she would rule out supernatural women, she adds. “I would love to play a character with magical abilities. I enjoy superhero movies as long as the story is well written and the characters have wit and heart, like Iron Man and Star Wars. Otherwise soulless characters in a plastic universe don’t appeal.”

Kathy Bates photographed for the Guardian. Photograph: Philip Cheung/The Guardian

Today, at 71, Bates looks chipper and fit. She came through ovarian cancer in 2003, but in 2012 had a double mastectomy after being diagnosed with breast cancer. After, she suffered lymphedema – a condition that makes the arms rock-solid as lymphatic fluid drains out under the fingernails, and which, she discovered, was barely understood by medical professionals.

“I dated a guy who had melanoma in his armpit and they took everything out and as a result his arm was like wood. I pleaded with my surgeon not to take any lymph nodes out.” He ignored her. Since then she has been raising awareness of lymphatic edema: “more people have it than MS, muscular dystrophy, ALS and Aids combined – and nobody knows about it.”

She is the spokesperson for the Lymphatic Education & Research Network. “I spoke before the American Society of Breast Surgeons and it’s so hard to convince them – Nobel laureates! I gave them these statistics and there were gasps in that room.” Though she likes Twitter, she mostly uses it for getting the word out about the condition. “I joined in 2011 and initially used it to engage with fans and then it got to be so time-consuming that I had to cut back. Then after a couple of unpleasant experiences with fans I rarely use it and I don’t get sucked into provocative tweets.”

She worries about a general “climate of hate” that’s “getting stronger in my opinion”, particularly when it comes to LGBT rights; in 2016 she was involved in a video telling the stories of victims in the Orlando shooting. “Viciousness is bred in the bone and will take generations to reverse. I worry about my gay and transgender friends.”

But Bates remains a bumper to the end. Next month is going to be mostly about awards ceremonies, and one Oscar victory and two losses have left her a perennial optimist. “I learned you always think you’re going to win, the moment they announce your name.”

Richard Jewell is released in the UK on 31 January

• This article was amended on 17 January 2020 because an earlier version misspelled Harold Clurman’s last name as Klurman. This has been corrected.