Gaga may, on occasion, draw heavily from the music and iconography of her heroes, but her influence on her own peers is even more obvious: Miley Cyrus and Christina Aguilera practically destroyed their careers trying to copy her; Rihanna and Katy Perry keep getting weirder (see Perry's "E.T." video); Ke$ha is allowed to be famous.
Not to mention the now-inescapable four-on-the-floor dance beats that Gaga reintroduced to pop radio – a sound she's now trying to reinvent.