I don't have figures and neither do I know how to dig them out, but I do know for a fact that IPL had considerable fan following in Pakistan for many years. In fact you can even dig up an article written by a Pakistani sports journalist back in 2013, on why the IPL is popular in Pakistan in spite of no Pakistani representation.
https://blogs.tribune.com.pk/story/17046/eight-reasons-why-the-ipl-is-popular-in-pakistan/
There are two main reasons why the IPL is more popular in Pakistan compared to other leagues like Big Bash and CPL. Firstly, the time slot for the IPL matches are suitable to the Pakistani audience. Big Bash is usually too early in the morning while CPL is usually too late in the night.
Secondly, and more importantly, a lot of people started following different IPL teams thanks to the Pakistani players in season 1. Fans of Afridi started to follow the now defunct Deccan Chargers, Akhtar fans started to follow KKR etc., and people started to invest in these teams.
GEO Super has telecasted the IPL for years and if there were no eyeballs, they would be losing a lot of money which hasn't been the case. You are right in stating that some people watch everything.
Forget IPL, there is an audience for Hong Kong Sixes and even that weird Ice tournament in Switzerland that took place last year. However, I have definitely noticed a drop in interest after the PSL. Since the IPL starts right after the PSL and is two months long, quite a few people have lost interest.
Also, because of the supposed rivalry between PSL and IPL, some people oddly feel that it is their patriotic duty to not watch the IPL anymore.