There's Mozilla Foundation and there's Mozilla Corporation (the corporation is a subsidiary of the foundation). For Mozilla Corporation:
> In CY 2018, Mozilla Corporation generated $435.702 million from royalties, subscriptions and advertising revenue compared to $542 million in CY 2017.
https://www.mozilla.org/en-US/foundation/annualreport/2018/ (I couldn't find a more up-to-date annual report)
For Mozilla Foundation:
> The Mozilla Foundation is funded by donations and 2% of annual net revenues from the Mozilla Corporation, amounting to over US$8.3 million in 2016.
https://en.wikipedia.org/wiki/Mozilla_Foundation#Financing