Seven is still popular, but it hasn't spawned any worldwide fandoms or anything. We think that's a good thing. The world doesn't need any crazy copycat killers running around.
The film did, however, inspire a brief comic book run and a sequel. Sort of. The 2015 film Solace was originally intended to be a sequel to Seven, starring Morgan Freeman's Detective Somerset. That didn't happen. At least they're not calling it Ei8ht.