Eminem is regarded as one of the most important artists in the history of the genre even though his albums haven’t been as genre-defining as so many of his peers, and his music is only tangentially influential when compared to a Rakim, 2Pac, Jay-Z or Kanye. He’s mostly important for providing white fans a credible entry point into the genre.
Personally? As a white man and a musical man, I have always been suspicious of white artists peddling themselves as rap / hip hop artists, even if their music sounds cool at times.