I think the interrogation/torture scenes pretty much warrant a PG-13 rating. Someone on TheForce.net claims that in one of their viewings parents covered their kids eyes when Kylo was mind probing Rey. Even as a 21 year old man I have found myself kind of uncomfortable when viewing that scene.
There are other things like Finn saying “Hell no”, his horrific injury at the hand of Kylo Ren, Poe’s face being bloody during the interrogation scene etc. that makes it obvious why this is a PG-13 film.
You can say “Hell” and even “Damn” in a G rated film. At least one used to be able to.