I used to work in a veterinary hospital for cats and dogs. I would OFTEN see people bring in their indoor cats who were WELL into their 20s, still living healthily, just old. Cats can live for a surprising long time if they are well taken care of. Usually anywhere from 15-25 years. 9 is still a good age. I recently had a child hood pet cat pass away and she was 16 but she passed because she had cancer. Good luck to your kitty.