Is A DSLR APS-C Camera More Likely To Create Creamier Bokeh than A Mirrorless APS-C?

Answering this question in multiple parts.

(1) as previously noted, Bokeh is 100% lens/sensor size specific. And Because any DSLR APS-C lens can be mounted on a Mirrorless APS-C body (via adapter, which is primarily a tube of air), any mirrorless APS-C camera can therefore produce the exact bokeh that a DSLR produces, by simply using the identical lens on an adapter.

(2) a completely different question is the issue of whether native mirrorless APS-C glass produces the same Bokeh as DSLR glass.

(2A) there are less native lenses for MILC available. With a smaller population of lenses, there is probably a smaller population of "great" lenses that make "great Bokeh"

(2B) The MILC glass is designed with a shorter flange focal distance, and I do not know how that design choice specifically affects Bokeh. Perhaps somebody here knows that Though. MILC lenses don't technically have to be put that close to the sensor, but putting it farther away would make the lens longer. So they are generally made with that short distance from rear lens element to sensor.