You're not affecting FOX News if you still subscribe to cable. They still get paid. Cut the cord.
If you just don't watch them they might lose advertising dollars but still get nearly $2.00 per cable subscription every month. That is the bulk of their revenue.
Also they can afford to take a temporary money hit for a year or so to rebrand their ideology but they are counting on you to come back eventually. If you cut the cord you never will.
Check out this article.
https://www.dailykos.com/stories/2020/3/31/1933075/-If-you-have-cable-you-are-subsidizing-Fox-News-It-might-be-time-to-cut-the-cord-Here-s-how
Isnt their ad revenue based on ratings?
Yes they do get revenue from ads but the cable subscription fees are their bread and butter.