How much does Igss vary with temperature?
To a first approximation, MOSFET gates don't leak at all, it's in the sub-pA range for small-ish MOSFETs at room temperature.
The &quot;typical&quot; spec of 2nA is a relatively heavy current and, if correct, indicates something else may be going on, like an internal gate protection network. That could double every 10°C.
If you have one on hand you may wish to make a quick measurement to see if there really is that much leakage at 25°C.