Can the gift be made of a property which is not in existence, i.e. of future property?

No. The subject matter of a gift must be a certain, existing, moveable or immoveable property. It could be anything such as, goods, any right, title or interest in any immovable property, which exists, or even an actionable claim. It must be transferable within the meaning of Sec.6 of the Transfer of Property Act. A gift of the right to management is valid. But a gift of the future revenue of the village is invalid. Release of a debt is not a gift; because it does not involve any transfer of property but merely a renunciation of a right of action.