Only God knows whether or not your uncle truly repented of his sins and trusted Christ for His salvation before he died - but if he did, God fully forgave him, and you can be confident that he is now in heaven forever. Jesus said, "I tell you, there is rejoicing in the presence of the angels of God over one sinner who repents" (Luke 15:10).
Remember: We are never saved because of how good we are, or because of how much we did for Jesus. In other words, we're never saved because we deserve it - never. We are saved only because of God's grace and mercy, and because of what Jesus Christ did on the cross for us. If your uncle truly accepted Christ, he was saved solely because he believed Christ died for his salvation. The Bible says, "For it is by grace you have been saved, through faith" (Ephesians 2:8).
Do you remember the two men who were crucified with Jesus? Unlike Him, they both were guilty - and in only a few hours, they both would die. One of them mocked Jesus and turned away in scorn - but the other turned to Jesus in faith and asked to be forgiven and saved. Jesus replied, "I tell you the truth, today you will be with me in paradise" (Luke 23:43).
Thank God for your uncle's salvation - but don't follow his example! Instead, open your heart to Jesus Christ without delay, and discover the joy of following Him the rest of your life.