Does A DSLR APS-C Camera Produce Creamier Bokeh Than A Mirrorless APS-C System?

The amount of out of focus (bokeh is the quality of this blur) is a factor of the focal length.

Hence, there is no difference between a aps-c dslr and a mirorless aps-c camera regarding "bokeh" if you use the same lens on the same aperture.

For example, a 50mm f/1.4 lens on a 600D will give you the exact same DOF as the same lens mounted on an Eos M.