From my understanding of the event (based on my working with Toby Marotta on the book The Politics of Homosexuality which included an elaborate account of Stonewall), what "empowered" the patrons at the Stonewall Inn was a general hippie/countercultural rejection of societal power structures (arising from the anti-war movement) AND, importantly, from a sense of numbers.
I think -- and I don't claim to be right, only to have an opinion -- what happened is that earlier that the day, Friday, June 27th, 1969, a great many men from the Village flocked to Judy Garland's funeral at a upper Eastside funeral parlor at Madison Ave and 81st. What impressed them -- and in the early hours of the next day, mobilized them to resist the police raid on the Stonewall Inn -- wasn't Garland's divahood (after all, it had been her downfall), but rather the number of other gay men they saw at the event. These were Garland's fans. There were crowds of homosexuals recognizing each other on the street in front of the funeral parlor.
Garland's funeral turned out to be a sort of proto-gay pride event. And it demonstrated there was power in numbers -- that was something "in the air" in those days as one anti-war mobilization after another demonstrated how many people were "anti-establishment."
The Stonewall Inn was a sort of hippie bar. The "street queens" weren't politicos and they weren't "drag queens" in the sense of female impersonators or drag performers. (The bar was not particularly welcoming to true drag queens/female impersonators and, in fact, had a quota on the number the bouncer allowed in.) They were hippies in so-called "gender fuck drag." And they were likely high on pot or tripping on acid.
The Stonewall Inn, in fact, had been under attack by the fledging gay politicos of the time. About a year and a half earlier, Craig Rodwell (previous President of the Mattachine Society New York and founder of the Oscar Wilde Memorial Bookshop) had written an article for a MSNY newsletter called The Hymnal tracing a rash of Hepatitis A infections to the bar. It was believed by the proto-actvists with the Mattachine that the bar didn't wash glasses between uses. This lack of concern for the patrons' well-being was attributed to the bar's Mafia ownership.
As time has passed, the mythology of Stonewall has come to valorize drag queens as the champions of political and cultural revolution. That's probably missing the point that it was the anti-Establishment tenor of the times, hippie nonchalance and joie de vivre, gay men's sense of being outsiders, and, very importantly, the drugs -- and then the sense of numbers and power observed at Garland's funeral -- that gave the patrons at the Stonewall Inn the impulse to resist the police that night. And inadvertently to initiate the transformation of how gay people see themselves that is the gay rights movement!
This was liberation through consciousness change. And that is our queer contribution to the effort of human consciousness to understand how to transform itself and save the future.