SPJ and a fe wothers work at microsoft, but they are few compared to the community. Likewise, several high profile haskellers were at Standard Chartered, but I don't believe this was significant.

I would say the main drivers of Haskell these days are academics, PhDs and consultancies.

SPJ is a Microsoft Research Cambridge employee, but as far as I know that doesn't give Microsoft Research (let alone Microsoft itself) any undue influence over the language's direction, they can't gatekeep or ram things into Haskell or GHC.

It would still be corporate sponsorship and not a true community effort though. Not having to work to pay bills makes it much easier to run a large project.

Pretty sure SPJ does have to work to pay bills. It's just that they work for a research institution and can thus do part of their work in / on the project. In no small part because CS research was one of the use cases for creating Haskell.

Majority of open source contributors have a day job.