What is a ferrets lifespan? how many years does a ferret live?

They usually live around 8 years but they can live longer.

The oldest I've heard of a ferret being is 10 (but I'm sure there are some that have lived longer), and that is very old for a ferret. Their average lifespan, I'd say, is between 7-9 years. But that is only with proper diet and vet care. Ferrets are prone to MANY illnesses, and it is very rare for a ferret to go through life without getting one of these diseases. The common ones include adrenal disease, insulinoma, lymphoma (and many other cancers), intestinal blockage, etc. Sadly, many ferrets end up with multiple of these diseases.

Everyones saying 7-9 :s but my aunts ferret just recently died, but he was 12 years old. I would say 7-12 yrs

Ferrets from the pet store tend to live 6-8, maybe 9 years with proper diet and vet care. This is because most pet store ferrets come from mass breeders such as Marshall. Marshall ferrets can be healthy (my ferret is a Marshall and he is healthy) but since they are mass produced, they breed generally low quality animals who are sometimes inbred and are prone to disease. Ferrets from a breeder can live longer because they are a higher quality and their ancestry can be traced unlike Marshall who keeps no records on breeding. Ferrets from other countries tend to live longer as well (some as long as 14+ years). So if you live in the U.S and don't get the ferret from a breeder, expect the 6-8 year lifespan.