Here's the list after the season 3 finale. The percent isn't the odds of death, but my confidence level that the character will survive relative to the character that I believe most likely to live. Also, I'm ignoring series finale possibilities.

100% - Tyrion Lannister - Why: ~Dinklage~PeterDinklage~PeterDinklage~PeterDinklage~

80% - Cersei Lannister - Why: Having more competent rivals(Tyrells) to deal with as well as reuniting with Jaime knocks her down a few points.

80% - Jaime Lannister - Why: Brought down for being near Cersei as well as becoming a more relateable character. He'll need to do some bad guy things in order to increase his necessity in the story.

0% - Catelyn Stark - Why: Well shit.

95% - Daenerys Targaryn - Why: Frees slaves like she was a part of House Tubman.

85% - Littlefinger - Why: He seemed like a more content person at first, but apparently he's greedier than I thought. His plans conflict with other characters, so he won't be around forever. Not enough time in a single season to build up his schemes for a fall though.

65% - Ser Jorah - Why: Yup, more conflicts over Daenerys with other male characters, as expected. Though I'm betting on him making it to sea before anything bad happens.

100% - Jon Snow - Why: A strong moral character, I guess. Pffft.

85% - Tywin Lannister - Why: Less living people that want him dead now. His strong will he imposes on other important characters makes him a bit problematic for the continuation of the story though.

35% - Ser Davos - Why: Stannis lasted longer than expected, and his survivability has a positive impact on Ser Davos, because Ser Davos lacks enough connections to other characters. Gendry helped with that though.

100% - Bran Stark - Why: Potential mind control user? That shit is fuckin' broke. WE CODE GEASS NOW.

0% - Robb Stark - Why: Marrying Talisa brought him in the danger zone. Still took me by surprise. Dang.

90% - Sansa Stark - Why: Keeping Dinklage tied down makes her a bit inconvenient.

95% - Arya Stark - Why: The Stark children will probably be reunited before any of them die.

75% - Theon Greyjoy - Why: Alright, so Rob's dead and they took an entire season torturing him to bring his karma back up. Here's to another season. Go Ramsey!

80% - Sam - Why: Yer a wizard, Sam.

80% - Joffrey - Why: People continue to get sick of his shit, but the people with influence over him would rather he be dethroned than die.

50% - The Hound - Why: Well, he definitely got some more development last season. Not too sure about this one.

60% - Stannis - Why: He'll be around for as long as Melisandre needs him.

65% - Melisandre - Why: I think her atrocities are going to ramp up quite a bit before she would die. I mean c'mon, a single human sacrifice isn't that big of a deal.

70% - Bronn - Why: I mean, he's made it this far. Why not keep him going?

85% - Varys - Why: His rivalry with Littlefinger will likely play an important part once that scheme progresses.

70% - Margaery Tyrell - Why: She's surprisingly power hungry and clever. I don't think she can manipulate Joffrey indefinitely though.

65% - Shae - Why: Tyrion is very attached to her. Since he can't die, she very well could.

85% - Gendry - Why: I suspect some things will go in his favor for a bit and he'll be given a chance to prove himself heroically at some point.