No, he isn't right—not at all. A large number of people witnessed Jesus' death, and the Roman soldiers who took His body down from the cross were hardened men who were familiar with death. They made certain Jesus was dead before they released His body.
Remember, too, that when Jesus was laid in a borrowed tomb (which was somewhat like a small cave), guards were placed around it to be sure the body wasn't stolen. In addition, a huge stone weighing hundreds of pounds covered the mouth of the tomb. It would have been impossible for someone who had had nails driven through his hands and feet to regain consciousness and move such a stone.
Jesus' resurrection is one of the most carefully documented events in history—and this is the foundation of our hope. The Bible says, "If Christ has not been raised, your faith is futile. ... But Christ has indeed been raised from the dead" (1 Corinthians 15:17,20).
Your uncle still may not be persuaded, however. His real problem, I suspect, is deeper: not doubt but disbelief. He knows that if he ever admits Jesus rose from the dead, he will have to submit his life to Him—and that is what he refuses to do. Pray for him, and ask God to help you share with him the hope we have in Christ, both for this life and the life to come.