Gold is just the "class of service" i.e. "Gold Choice" as opposed to "Counter". As long as you have your Pres Circle account attached to the reservation you'll be allowed to choose from the Pres zone the day of your rental.
If you're signed up for Hertz Carfirmations, you may receive an email like this (or maybe not, given how bad Hertz's IT is) the day of your rental more clearly indicating your status as Pres Circle: