How can one tell if a non-blooming aucuba is male or unfertilized female?

You tell the difference by the blooms. Female blooms are close to the leaves. Male blooms are raised up and away from the leaves on panicles. I don’t know for sure, but I doubt putting them in pots would make any difference in the “fertility.” They still need wind or insects to pollinate them. Call your local county extension agent. They are usually a wealth of information.

I agree with everything @bkcunningham said above and would add that if you take a photo of yours in bloom and email your local extension, an expert will most likely email you the answer withing 24hrs that’s what happens for me every time i’ve had an insect or flora question to be answered

There have been no blooms on any plants for 10 years. I just bought a small blooming aucuba. I want to know if there are any males left in residence to fertilize it among the 2 large and 3 small plants I already have. How can I identify their gender?