A quality modern semi-auto is as reliable and durable and durable as a quality modern revolver. Both should last many thousands of rounds before you need any work done to them.
There are way too many variables to determine which type of gun would outlast the other....type of ammo, shooting styles, climate, storage conditions, maintenance, etc.
Choosing a quality revolver vs. a quality semi-auto should really be based on factors such as 1) ease of use, 2) concealability, 3) safety system(s), 4) capacity, 5) recoil, 6) ergonomics, 7) caliber perfered, and let's not forget 8) look and feel fo the gun.