Will my gourami be okay...!?

A 2.5 gallon is not OK for any fish. Not even a Betta. Depending on the Gourami will tell you what kind of tank he needs. A dwarf, like 10 or 15 gallons. If you have that much Ammonia and NitrAtes, the tank was not cycled. And even the smallest bit of ammonia stresses the fish out. So that really needs to be corrected. And so do the Nitrites. Your NitrAtes are good right now. But as for the rest, they are not. So I would either return him, or do some daily water changes when cycling a bigger tank.