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?
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.
Just to be precise, Firefox development is lead by Mozilla Corporation, which in theory is a for-profit company; however it is fully owned by the Mozilla Foundation, and all profit is reinvested to the Mozilla project.