That is one cool looking beetle. How long DO they live?
I'm not sure how long it takes the eggs to hatch. It can take the larvae up to a year before they go into the pupae stage (and look like little beige Alien facehuggers). I think it took 4-6 weeks before they emerged in all their horned splendor. Males live about 4 months; females live a bit longer if they haven't had the opportunity to breed (since they die after laying their eggs).
We had bought a container with 4 of them (two still in the larvae stage, one just turning into an Alien, and the third completely in the Alien phase. (Calling them Aliens instead of pupae is old habit).