Samuel Irving Newhouse Jr, known as Si, was the elder, less favoured son of tough old Sam Newhouse Sr, who built an American press empire one local paper at a time and whose wife, Mitzi, loved Condé Nast’s Vogue magazine so much that he bought her the company as an anniversary present.

Sam prepped his younger, more streetwise son, Donald, to take over the newsprint and inserted shy Si in the high-shine Condé Nast magazine company. Si Newhouse, who has died aged 89, took the china-clay-surfaced, ad-magnet pages and its few publications and turned them into a shelf of global magazines all his own. He launched, revived or shut them, and took the decisions to hire and fire their editors.

You may not have heard of the family business, Advance Publications, its solid papers and TV stations that were for decades a licence to print money; but you will know Vogue, the New Yorker, Vanity Fair, GQ and Wired. Newhouse personally read those magazines right down to the text on their spines and queried the typography of the captions. He even knew how many readers renewed subscriptions, which allowed him patience with magazines in turmoil. That knowledge took time to accrue.

Facebook Twitter Pinterest Si Newhouse with Donald Trump in 1987. Photograph: Sonia Moskowitz/Getty Images

He was born in Staten Island, New York, and attended the Horace Mann school. He was no scholar, dropping out of Syracuse University and quietly joining the family firm in the early 1950s. Newhouse Sr bought Condé Nast in 1959 and with it came Alexander Liberman, its editorial director. As well as taking to the glossies, Newhouse Jr took to Liberman, bonding over art. Liberman painted and had access to the art scene; Newhouse collected at the highest modern level, always prepared to pay for the best. Liberman demanded extravagant talent for Condé Nast and Newhouse said yes, which is how Vogue acquired Diana Vreeland as editor in 1962, and Richard Avedon as star photographer.

Vreeland’s astounding, outstanding Vogue was both a last gasp of old-style magazines produced for the movers and shapers of fashionable society and an intimation of Newhouse’s new world of buzz, glitz, heat, celebs, self. Her Vogue was flagrantly successful in its extreme dreams until, with a loss of cultural exuberance around 1970, it wasn’t. Vreeland was dismissed peremptorily in 1971 in what came to be Newhouse’s signature mode – indirect communication (so indirect that the victim might hear their fate first on television news), with calm negotiators handling the severance package.

Facebook Twitter Pinterest Si Newhouse with Tina Brown in 1990. Photograph: Ron Galella/WireImage

Newhouse took over as chairman of Condé Nast formally in 1975, and with his brother inherited Advance Publications on their father’s death in 1979. He launched Self in 1979 for a new market that believed health, fitness and beauty to be purchasable commodities and backed the reworking of GQ from a camp publication into something more blokey in 1980. He hankered for that marker of Manhattan sophistication, the New Yorker, but, since it was not then for sale, settled for resurrecting Vanity Fair.

It was in panic and limbo for a while, then, after two outmoded editors had met their severances, Tina Brown was flown in from London in 1984. Her Vanity Fair was the very brightest glow of Newhouse’s gilded age, based around moneyed and powerful players in politics, arts and entertainment. It treated the 20th century as if it were the 18th, when only a very few people were thought to matter, yet it did so with the attitude and skill of the great Georgian caricaturists. Eventually, it even made a profit.

Newhouse finally bought the New Yorker in 1985 for the unreasonable price of $200m, and dispatched its venerable editor William Shawn with the usual ruthlessness. (Brown was forwarded to it in 1992, to heat it up.) Another London import, Anna Wintour, landed at US Vogue in 1988, her mission, well-executed over decades, to integrate Vogue in Newhouse’s universe, supplying fashion as Architectural Digest and World of Interiors did shelter, Bon Appétit and Gourmet food, Condé Nast Traveller destinations, and Wired IT updates. The publishers Random House, bought by Advance Publications in 1980, supplied extracts, authors, publicity and readers.

Newhouse’s editors were magnificently wasteful, with millions of unused but paid-for pictures and copy thrown away by fresh regimes, and reshoots upon reshoots. He loaned staff his absolute power over creative decisions: there were no board meetings to convince or stockholders to please. Newhouse was equally munificent with million-dollar-plus salaries for his editors, clothes allowances and limousines, and interest-free loans to buy appropriate homes. Brown, finding Newhouse impenetrable, brought in a big league agent to negotiate a salary, only for Newhouse to offer to pay her ageing parents’ medical bills for life to ease her worries.

Advance Publications was a family business, without need to disclose earnings or expenditure, and so implacable over taxes it fought the IRS. Newhouse’s universe developed a black hole in the mid-90s when more than half of Condé Nast’s publications were revealed to be millions in deficit. He retrenched, with losers shut, Random House sold and costs cut, and then had to shrink again after 2008, when all magazines mutated and diminished because of the global financial crash and the intervention of the internet.

Brown thought Newhouse ultimately unknowable. The designer Lucy Sisman, working for him in his peak years, remembered a “short, scruffy billionaire who was often mistaken for a janitor by an unsuspecting employee who didn’t think their boss might sport a sweatshirt with dribble down the front”, albeit one who had Piet Mondrian’s Victory Boogie Woogie among the many masterpieces on his walls. Newhouse maintained two Manhattan homes – one as a home, and a second for entertaining. Not that he was likely to be in either of them, since he arrived early at Condé Nast’s Times Square HQ, available on the phone to mumble about work before the city was awake. He was happier lunching in its Frank Gehry-designed cafeteria than at the Four Seasons.

Newhouse’s family life was as discreet as the business. There was a youthful marriage to Jane Franke, with children Sam, Wynn and Pamela, which ended in 1959, and in 1973 a second, to Victoria Carrington Benedict de Ramel.

Wynn died in 2010. Newhouse is survived by Victoria, Sam, Pamela and Donald.

• Samuel Irving Newhouse, publisher, born 8 November 1927; died 1 October 2017