Canon G1 X III has a 24.0MP APS-C (22.3 x 14.9 mm ) sized CMOS sensor and features DIGIC 7 processor. On the other hand, Fujifilm S2 Pro has a 6.0MP APS-C (23 x 15.5 mm ) sized CCD sensor .
Canon G1 X III's sensor provides 18MP more than Fujifilm S2 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 G1 X III and S2 Pro sensor size comparison.
Canon G1 X III and Fujifilm S2 Pro 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.