Not really two poles, because any gate leakage is parallel to,
not in series with, the gate oxide capacitance. Say your gate
access resistance is 10 ohms, your leakage at Vgs=10V is
10nA and your Cgg is 10nF. That makes your network give
a corner frequency of 1/(2*pi*10*10E-9 or 1.6MHz. This
would indicate the so-parameterized FET is not a good idea
for >1MHz switching.
The leakage "resistance" is a shunt, not a series, resistance.
It does not contribute to gate RC in any meaningful way and
does not create a 0.016Hz pole, as evidenced by the fact
that people find the devices useful for anything at all.