Fujifilm S5 Pro has a 6.0MP APS-C (23 x 15.5 mm ) sized CCD sensor . On the other hand, Sony A6300 has a 24.0MP APS-C (23.5 x 15.6 mm ) sized CMOS sensor and features BIONZ X processor. Sony A6300's sensor provides 18MP more than Fujifilm S5 Pro'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 S5 Pro and A6300 sensor size comparison.
Fujifilm S5 Pro and Sony A6300 have almost the same sensor size so none of them has any significant advantage over other in providing control over depth of field when used with same focal length and aperture.