Depending on the resistor connected between GRC and ground, the gate drive can be set to one of the values listed in table below:
These resistors configure the device for different soft start ramp rate as shown in the table. For 10ms ramp rate on the gate, the expected gate to source capacitance is determined by Cdv/dt = I -> C = (5µA *10ms)/9V = 5.5nF. If the capacitance is more than 5.5nF, the gate will require more time to reach its final voltage level but because of the 10ms soft start limitation, it will enter a fast mode and suddenly jump to its final value.