JRPG is fairly meaningless as a minker, but it's literally Japanese Role Playing Game which Dark souls is. Otherwise, I'm not sure what the distinction would be. Does a JRPG need to be turn based or something similar? Like what separates dark souls from an action JRPG? Does it need to have an anime-esque aesthetic to be considered a JRPG (dark souls takes heavy influence from berserk, so I think it'd still qualify honestly) ? Personally, whenever this discussion comes up, it's always sounded like "I don't particularly like JRPGs, but I love dark souls, so clearly it's not a JRPG".
It's partly why I don't like the JRPG and WRPG monikers in general. They're labels with very little meaning now-a-days.