Panasonic GF8 has a 16.0MP Four Thirds (17.3 x 13 mm ) sized CMOS sensor and features Venus Engine processor. On the other hand, YI M1 has a 20.0MP Four Thirds (17.3 x 13 mm ) sized CMOS sensor .
Below you can see the GF8 and M1 sensor size comparison.
Panasonic GF8 and YI M1 have sensor sizes so they will provide same level of control over the depth of field when used with same focal length and aperture. On the other hand, since Panasonic GF8 has 27% larger pixel area compared to YI M1, it has potential to collect more light on pixel level hence have less noise in low light / High ISO images.