RV gasoline life span in long term storage

might be ok, pour a couple cans of sea foam in it and drive it around about twenty miles. then use that fuel up as soon as you can.

You'll be fine. How long do those unwanted new cars on the lot sit before they drop the price in half?

Stabil states 2 years.

Sorry to hear about your difficulties. Was any fuel stabilizer used prior to parking? If so, it’s probably OK, but I wouldn’t personally go past two years even with stabilizer.

If it was not treated, it depends on the conditions, temperature, humidity, how full the tank is. Over a year could be to the point of degrading already. If it was mine, I’d put some Techron fuel system cleaner and some octane boost in the tank and hope for the best. Probably that will get you through that gas and you can drive it out and get fresh gas.

It’s impossible to be certain of the situation until you get into it. Could be no problems; could need fuel filters, worst case it could need the tank dropped and drained.

Without stabilizer and with ethanol, "over a year" is not good.
It kind of depends on how much over a year......and what the quantity is.
A large tank will fare better than a small one.