Martin Scorsese was attached to produce, and the film is influenced by Taxi Driver, Raging Bull and King of Comedy
https://en.wikipedia.org/wiki/Joker_(2019_film)
Scorsese had to drop out last year due to other obligations, but they were angling to get Leonardo DiCaprio as the Joker.
Robert De Niro is in this film and plays a TV host. He confirms it's a nod to Rupert Pupkin but not the same character.
https://www.indiewire.com/2019/04/robert-de-niro-joker-king-of-comedy-1202055636/