Fujifilm S9800 has a 16.0MP 1/2.3" (6.17 x 4.55 mm ) sized CMOS sensor . On the other hand, Canon 20Da has a 8.0MP APS-C (22.5 x 15 mm ) sized CMOS sensor .
Fujifilm S9800's sensor provides 8MP more than Canon 20Da'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 S9800 and 20Da sensor size comparison.
Sensor Size and Resolution Comparison image of Fujifilm S9800 and Canon 20Da Cameras
As seen above, Canon 20Da has a 12.0x Larger sensor area than Fujifilm S9800. Larger sensors give photographer more control on the depth of field and blurry background compared to smaller sensor when shot in same focal length and aperture.