[FooBarBizBazz]

I had to think about this but my answer is boring: "He picked the right themes and aesthetic at the right time."

Cyberpunk would have happened without him (Blade Runner was released first), but most things are like that.

He'd also studied English, which helped give him some sensibilities that would appeal to tastemakers. Neuromancer wasn't genre fantasy and it wasn't hard SF. (Even then, the name turned many people off.)

And I guess he won some powerful allies early on in what was then the SF establishment.

[Apocryphon]

Gibson's first story, "Fragments of a Hologram Rose", published in 1977, really shows off his literary education. It's got a real dreamy style to it.