Note that you cannot use the non-pro version if your company has a turnover above $100k/year.
My reading of that is that it is the total revenue of the company, no matter how small the Unity project might be.
But I wonder how it works if a company with that much gross revenue hires a third-party that does not make that much revenue to create the content for them. I guess the rule would apply to the third-party.
Hmm, 100K is about the salary for one developer - how can a gaming company not have revenue of at least that amount? Unless it's a side project people do in their spare time?