Both Fujifilm X100T and Fujifilm X100S have 16.0 MP resolution sensors but Fujifilm X100T's sensor is APS-C (23.6 x 15.8 mm ) and Fujifilm X100S's sensor is APS-C (23.6 x 15.8 mm ).
Since Fujifilm X100S's has a larger sensor area with the same resolution, this means that it also has a larger pixel area hence better light collecting capacity for a given aperture compared to Fujifilm X100T.
One other difference between these two cameras that is worth mentioning is that Fujifilm X100S's sensor doesn't have an anti-alias (Low-Pass) filter. Removing anti-alias filter increases the sharpness and level of detail but at the same time, it increases the chance of moire occurring in certain scenes.
Below you can see the X100T and X100S sensor size comparison.
Fujifilm X100T and Fujifilm X100S have the same sensor sizes so they will provide same level of control over the depth of field when used with same focal length and aperture.