A cat's lifespan depends on many factors, including breed, lifestyle, and diet. Outdoor kitties tend to have a shorter lifespan because they face elements indoor cats don't.
In general, most cat breeds are expected to live to around 12 years old, but some make it to 18 or 20. This is a huge age gap! This is also why veterinarians usually say, "Age itself is not a disease." You might be blessed with an animal that could live to a ripe old age with proper medical care.