Thalapathy Vijay's remuneration for his last movie (to be directed by H Vinoth) is said to be Rs 275 Cr. For 'The Greatest Of All Time', his fee was Rs 200 Cr. He is earning way above Prabhas, although the 'Salaar' actor is vastly more popular than him.
Vijay is part of an industry sans able competitors. The Tamil audience have been deprived of heroic heroes. Ajith is a superstar but he looks somewhat too elite and far less flexible than he should. Suriya, Karthi, Vishal and other heroes can't get the mass audience to go delirious. If Rajinikanth is still a superstar even at 70, you can imagine how starved the Tamil audience are.
Prabhas, on the other hand, is part of an industry full of mass heroes. The Telugu audience's appetite is quenched by a lot of other heroes. Vijay benefits massively from the Tamil diaspora who watch even his utterly mediocre movies because he is the only superstar. If they don't watch a bad Vijay movie, they get to watch worse Tamil movies.
On the other hand, if the Telugu audience miss out on 'Saaho' or 'Radhe Shyam', they get to watch 'Pushpa', 'Pushpa 2', 'Akhanda', 'Waltair Veerayya', 'Bheemla Nayak', 'RRR', 'Devara', 'Vishambhara', and a lot more. You have Nani, Vijay Deverakonda, Ram Pothineni and Bellamkonda Sai Srinivas trying to please the mass audience.
Vijay is a beneficiary of the scarcity that ails Tamil cinema. Had a film like 'Sarkaru Vaari Paata' been done by an Ajith or a Vijay, it would have been a blockbuster.