Explain: “Moths and all sorts ugly creatures,” replied Estella, with a glance towards him, “hover about a lighted candle. Can the candle help it?”

Pip is admonishing Estella for the attention she receives from other men (in this case Drummle) and her response to his inquiry. She is the flame and it's her beauty that draws the moths (men) to hover around her. In her eyes, they simply cannot help themselves.