He still will have to go some to beat Tony Curtis. Curtis’ estate was valued at one billion and most of that was not from his movies, but his own art.
This where the subjectiveness of art comes into play. I just looked at his paintings. To me, no way they are worth the price except for the fact they were painted by tony curtis
there are some originals up for sale
https://www.artsy.net/artist/tony-curtis