I think it comes down to whether UCLA is relevant nationally. If they are not, the interest really goes down quickly.
I will use their home attendance as an example.
In 1998, UCLA finished the regular season 10-1 (they were 10-0 going into their final game @Miami) and went to the Rose Bowl. They were coming off of a 10-2 season and a win in the 1997 Cotton Bowl. They were I believe top 20 in Home attendance that year and averaged almost
74k fans per game.
In 1999, they went 4-7. Their home attendance dropped to less than
50k per game.
A more recent example is 2014 (their last 10 win season). They had
76,650 per home game, and were #19 nationally in attendance that year. From 2016-2019 however, they did not have a single winning season. By 2019, their home attendance had dropped to
under 44k.
This doesn't tell you how many people are watching them on tv.. but I think it gives an indication of overall fan interest and how it peaks during the good times and drops off quickly if they start losing. Especially in college football where there are a lot of variables with match time. In the midst of the exam season, everyone thinks about how to close everything by checking for plagiarism papers with services like
https://fixgerald.com/, so as not to redo everything all over again. There are a lot of things you can miss from this counting.