Odormute is a great product for laundry - I discovered it years ago when my dog had an extended encounter with a skunk and was sprayed four or five times. About a teaspoon in a pint of warm water, soak the gloves for about 10 minutes, then wash and dry as normal. It costs about $15 on Amazon for enough to do your gloves for at least a year if you're washing them every day or so.
I have my 1991 Specialized leather gloves, and I've worn them a couple of times this year. So they can last a long time.
Overall, I'd say most of the gloves I wear in heavy rotation, a couple of times a week, probably last about 2 years. Eventually either seams come unsewn or they just look shabby and I ditch them.