It’s worse than that. They get paid by their advertisers for the numbers of people they “reach.” So as their viewership declines, so does their ad revenue. Advertisers will go elsewhere to place ads where there are more viewers, like Fox. But have you noticed that Fox has the prescription drug business about sewed up?
They also get a small portion of each and every cable subscriber’s monthly bill... for those who haven’t yet cut the cable, maybe now?