Kasputin
Surely you mean "Kapustin". How could you forget the most famous example: Gershwin?
Perhaps he meant Rapustin.
The example of Gershowitz that you mention is not quite as straightforward as it might at first seem; whilst in no wise seeking to undermind him, where would one realistically draw the line between actual jazz and "jazz influence" in his work? The dividing line is surely quite frequently blurred, just as is that between composition and transcription in the works of some of the great transcribers such as Liszt and Godowsky (of whom the latter was of course related to George G).
and there must surely have been many more who at one time or another have composed in a way suggestive of having been affected by jazz
Surely quite literally hundreds. Ernst Krenek, Ronald Stevenson, Antheil - and more I could name but my wife's just announced dinner.....
Interesting that you mention Krenek - a sadly underestimated composer who first two symphonies and other works all written before he reached the age of 25 deserve to be far better known than they are