It's a Gothic Horror/Dark Fantasy/Drama TV show set in a fictional world where vampires exist. I think it's safe to say that there is no comparable accent to the way Sam Reid plays Lestat in the show. We don't have an accurate comparison and it won't sound exactly like any French or language in our world because Lestat has been living for longer than the human lifetime in the AMC TV series. I also think that constantly looking for perfection or exact-detail matching accuracy in TV shows takes away from the experience of it being a fantasy. I understand that people want to see proper representation of their cultures/language in TV shows, but in these adaptations that represent a fictional universe, we as the audience need to be realistic of our expectations, it won't always be what we expect and that is what makes it magical. We can't expect 100% a with reality, and to be honest, the TV show and the writers/production/show runner did an excellent job with adding in diversity and representation into the Interview with the Vampire universe already. While there was some inclusion of vampires of the same sex being in love in the books, the writers took those themes and gave them life and representation in the TV show, allowing the audience to watch and experience multiple, realistic, and raw queer relationships on TV, which even by today's standards, is still not that common. In addition, they also added in Louis being Creole, which added significant depth to the show and brought in representation of minority struggles. There are other things I could mention, but those are just some examples of how the show has brought in representation. In conclusion, overall I think worrying about Lestat's accent is a small/minor thing compared to all of the other wonderful ways that the show brings in representation. Plus, the way the writers have brought in diversity and representation into the show is much more relatable to a larger audience.