There's a nonprofit Mozilla foundation that takes in about $20,000,000 and there's a Mozilla for-profit company that takes in about $350 million each year (it seems mostly from Google paying to set the default Firefox search engine.) And the nonprofit owns the for-profit company, which makes IRS tax accounting interesting. And that income should be enough to keep 1,000 employees paid, even in Mountain View, and even with the top three execs at the company getting paid about $1M each.