Increasing the gain (aka amplification, defined for this purpose as voltage at the input to the analog to digital converter divided by number of electrons counted) has the potential to reduce input-referred read noise (particularly if the conversion gain is increased by reducing the size of the pixel capacitor). The improvements may be small once the gain has been increased past a certain point. The downside is clipping the ADC before the sensor saturates.
That has some jargon in it. If you don't understand a term, ask me and I'll explain.