In general, I think small dogs tend to live longer. However, I believe the oldest living dog ever was an Australian Cattle Dog who was around 23..... *edit* it was a 28 year old Beagle that died in 2003.
I've read of some Yorkies living to be 20+.... however I think the general lifespan of a Yorkie probably ranges more in the 13-15 age range.
I think everything depends on genetics, lifestyle, food, etc as well.