I've read various accounts, but somewhere between 10 and 20+ years. I think it depends on success with their husbandry, as all things usually do. These guys are pretty straightforward and "easy", if you have basic herp experience. They're personalities vary and all that, too.
In fact, I'm about to get Lucille out and handfeed her... but I'll have to watch for her roommate, Val, cuz she likes to bite me when she's gravid.