Everyone knows Seinfeld's show within the show about Nothing. Supposedly George's idea, but George was channeling Larry David, so it is really Larry's idea for the entire series. So when I ask whether Seinfeld ripped off Warhol, I really mean to ask whether Larry David did.
Here is what I found in Warhol's wikipedia bio:
Television: Andy Warhol dreamed of a television show that he wanted to call The Nothing Special, a special about his favorite subject: Nothing. Later in his career he did create two cable television shows, Andy Warhol's TV in 1982 and Andy Warhol's Fifteen Minutes (based on his famous "fifteen minutes of fame" quotation) for MTV in 1986.
Maybe rip off is too strong. Maybe Larry and Jerry brought Warhol's vision to fruition. In either case, they did a much better job than Warhol could have dreamed.