Is that shape in the Chrysler MTC 2TC image a cupola?

The shape alone doesn't confirm what it is. If it sits on the turret and has visible hatch or viewing details, a cupola is plausible. If it blends into the scene, it could be part of the background. A clear close-up would help tell.

Even if the artwork makes it look like a cupola, that doesn't confirm the vehicle's actual features. You'd need a clear vehicle reference to distinguish a real turret detail from an artistic choice.