The amount you need to trade gold depends on your broker's XAUUSD specifications and how much you plan to risk per trade. A responsible starting balance should cover the required margin while leaving enough equity for the stop loss, spread, and normal price movement. There is no one-size-fits-all dollar amount.
Start by deciding how much of your account you are willing to risk, then choose a stop-loss distance and calculate the corresponding XAUUSD position size. Compare that position with the broker's minimum volume and margin requirement. This approach is more useful than choosing an account size from a generic minimum because gold volatility and contract specifications vary.
Risk note: Never risk an amount you cannot afford to lose.