It would be hard to say without test breeding him, since all the mixes can look alike. If you breed him to hens that lay brown eggs, if he's an olive egger, some of the female chicks that hatch would lay olive/green eggs. If he's a a Sapphire Gem, they'd all lay brown eggs. That's gonna be your...
If these are truly bred correctly - and Hoover hasn't had the best track record with breeding this breed correctly - then all chicks that are solid colored are females, and all that are barred are males.
I also think they lay brown eggs, not olive, unless they are now making even more crosses...