Far from it. looks what happen with istio.

that for sure is false... Google helped start CNCF but now plays a small part in its governance, they are just one board member like the 30+ others... they have no special voting rights...

https://www.cncf.io/people/governing-board/

they still do quite a lot of heavy lifting though in contributing to a variety of CNCF projects if you look at the numbers: https://all.devstats.cncf.io/d/5/companies-table?orgId=1

What happens to CNCF if Google backs out of it tomorrow? Including all funding?

you can see our finances here in the annual report: https://www.cncf.io/cncf-annual-report-2020/

fiscally the impact would be a membership fee which is a small percentage of revenue

The organization is fairly well diversified in terms of members and revenue sources but we appreciate Google's continued support in helping the organization grow, we think it's benefited them in projects like Kubernetes where the work is done by a larger community all working together: https://www.cncf.io/cncf-kubernetes-project-journey/

That's good, but Google is still the single biggest Kubernetes contributor. If they decided to take their ball and go home, it would leave the project in the lurch. It's a risk factor. Is it likely? No. But it's not outlandish.