I am making a new player character and in their backstory, their brother draws the Donjon card from the deck of many things:
Donjon. You disappear and become entombed in a state of suspended animation in an extradimensional sphere. Everything you were wearing and carrying stays behind in the space you occupied when you disappeared. You remain imprisoned until you are found and removed from the sphere. You can't be located by any divination magic, but a wish spell can reveal the location of your prison. You draw no more cards.
The card specifically says they leave all of their items behind.
How long someone could survive in the sphere? Since it's an enclosed sphere and they have no items, couldn't they starve?
I want to hint that he is still alive, but since it's been two years in-game since he drew the card, I don't know whether he would be alive or not.