Having eaten there back then I can say that the restaurant was definitely called 'Ohana before Lilo & Stitch came out. Both the restaurant and movie use the term in a similar manner so I guessed that 'Ohana meant family. The wikipedia entry indicates this as well.
I'd be surprised if the filmmakers didn't know about the restaurant (they are both Disney after all). I was rather surprised, however, at how long it took before Lilo & Stitch showed up at the character breakfast there.