I tried to verify that (I had thought that the timelines wouldn't have permitted that to be true). To my astonishment, Andy Kaufman did actually drive out to Las Vegas in 1969 to meet Elvis. Leno was born in 1950; his Wikipedia entry makes no mention of Elvis, but I suppose that he, too, might have done an "Elvis" impression that came to Presley's attention.
Regards,
I saw the show with Dick Clark. I did remember Leno doing Elvis back when The King was still alive. Kaufman did Elvis often about the same time. Here’s one vid;
https://www.youtube.com/watch?v=r59AWfhwpPg
Here’s Andy in a Fonzie look alike contest. Could not be done today.
https://www.youtube.com/watch?v=mXg6MpH68L0