Panasonic S1R has a 47.0MP Full frame (36 x 24 mm ) sized CMOS sensor and features Venus Engine processor. On the other hand, Canon 5DS has a 51.0MP Full frame (36 x 24 mm ) sized CMOS sensor and features Dual DIGIC 6 processor.
Another difference between these two cameras is that Panasonic S1R'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 moire occurring in certain scenes.
Below you can see the S1R and 5DS sensor size comparison.
Panasonic S1R and Canon 5DS have sensor sizes so they will provide same level of control over the depth of field when used with same focal length and aperture.