From a linguistic perspective, Occitano-Romance is more closely related to the langues d'oïl than to Ibero-Romance (despite the superficial resemblance of Catalan/Aragonese to Spanish), but not so closely that I'd agree with calling it "French." Culturally, certainly, langue d'oc was "French," and for a time it was more significant than any one langue d'oïl. (Actually, the state of Occitano-Romance, both Occitan and Catalan, is rather saddening, as I find them the most aesthetically pleasing of all the Romance languages.)