In a residential garage w/o temp extremes, prolly actually something like 25 years, or until the plastic bottle ages and cracks and it's all over the floor ...
The oil will last at least 10 years (if not more) in a temp-controlled environment. The biggest thing I would suggest to you is putting some Stabil 360 in the gas (and run it for a few minutes to let it get through the lines) before garaging it.