Rihanna is no way influenced by Gaga , she said in an interview that she will never wear something like what Gaga wears( 'Only Gaga could wear something like that') , but it seems that Katy and Minaj are trying to reach 'Gaga level'. But they still don't have the wow factor.
Sings half naked, "wow" performances, everyday another wig,... that's what I mean with gone "Gaga"