Sony A6400 has a
24.0MP APS-C (23.5 x 15.6 mm ) sized CMOS sensor and features Bionz X processor. On the other hand, Nikon D1H has a
3.0MP APS-C (23.7 x 15.5 mm ) sized CCD sensor .
Sony A6400's sensor provides 21MP more than Nikon D1H's sensor, which gives a significant advantage in real life. You can print your images larger or crop more freely.
On the other hand, please keep in mind that Max sensor resolution is not the only determinant of resolving power. Factors such as the optical elements, low pass filter, pixel size and sensor technology also affects the final resolution of the captured image.
Below you can see the A6400 and D1H sensor size comparison.
Sony A6400 and Nikon D1H have almost the same sensor size, so neither of them has any significant advantage over the other in terms of providing control over depth of field when used with the same focal length and aperture.