If it has a vascular connection, hasn't wilted, it is possible it could repair itself enough to survive. Leave it taped for now, support it with the stake, and see what happens. Long term, if it lives, you will need to keep it permanently staked, IMHO, because it will always be very weak at the break. But many of the very dwarfing root stocks make very weak trees that need staking, anyway, so that's probably not a big deal.