How does it work anyway? I mean, how does Firefox make money? Are they paid per google search or something like that?
And, do they make money if I use forks of firefox and use Google on them?
And, what are the total number of active users for Mozilla and do the forks account into this count?
They get paid by Google just to keep existing as a competitor
Afaik the deal between Mozilla/Firefox and Alphabet/Google is that Mozilla receives funding for setting Google as the default search engine. When the user decides to change that after install it has no influence on that contract.
My guess is that the deal is based on Firefox’ market share, so as long as the fork identifies as Firefox by user agent, this shouldn’t influence it at all.
There can be only estimations, either based on market share analysis or build-in telemetry.
Firefox is a piece of open source software. One can download it for free. It’s packaged by many different organizations for use in different settings.
In general, if a developer is modifying Firefox for their own needs, logging data would probably still report it as Firefox even if the browser has been renamed. Of course that could be changed if a developer wanted to do so, and as a user you can even install plugins that allow you to spoof browser profiles.
There is an NPO called The Mozilla Foundation that develops Firefox, although many contributions come from people who are not part of the foundation. If you’re asking how much money the NPO uses, I think you can go take a look at its books. It is an NPO, so making money is not the objective.