$75 million per year from subscriptions and ads, according to their latest report (2022 for some reason). Another commenter did some quick math to try to prove that donations were fruitless and found that Firefox could reasonably expect to replace that revenue with a donation box:
How do you measure impact? If it's income created for Mozilla Corp then I agree it's impactful too, and the CEO's pay does seem justified.
> How successful are they with their side projects, anyways?
Honestly I don't know, I haven't looked at their latest annual report. I do pay for Mozilla VPN, although I'm not a Firefox user.