What foundation? If you mean Steem Foundation, there was promised some initial contribution by Steemit, Inc., but the large STEEM stake remains Steemit's. So is the stake from misterdelegation and a few other smaller accounts. As far as I know, if nothing changed in the meantime.
Steemit, Inc. does provide the most used nodes for the ecosystem. When they were down, pretty much nothing moved back then, hopefully things improved a bit.
They also have the main team which works on the blockchain code. And other coding stuff. Human resources matter.