Both Pentax K-70 and Sony A65 have 24.0 MP resolution sensors but Pentax K-70's sensor is APS-C (23.5 x 15.6 mm ) and Sony A65's sensor is APS-C (23.5 x 15.6 mm ).
Since Sony A65's has a larger sensor area with the same resolution, this means that it also has a larger pixel area hence better light collecting capacity for a given aperture compared to Pentax K-70.
Another difference between these two cameras is that Pentax K-70's sensor lacks anti-alias (Low-Pass) filter. Removing anti-alias filter increases the sharpness and level of detail but at the same time, it increases the chance of moiré occurring in certain scenes.
Below you can see the K-70 and A65 sensor size comparison.
Pentax K-70 and Sony A65 have the same sensor sizes so they will provide same level of control over the depth of field when used with same focal length and aperture.