Yes, I believe God is giving him a second chance -- and I pray he won't ignore it or laugh it off. God loves your cousin and wants him to discover the joy that can only come from knowing God and being in His presence forever. The Bible says that God "is patient with you, not wanting anyone to perish, but everyone to come to repentance" (2 Peter 3:9).
Situations like this should remind us that life is short, and we never know how long we'll have on this earth. Your cousin didn't plan on having a heart attack; he probably thought he'd go on living for many years. Perhaps he is like the rich man in one of Jesus' parables who said to himself, "You have plenty of good things laid up for many years. Take life easy; eat, drink and be merry" (Luke 12:19). But God called him a fool, and that very night he died and entered eternity -- without God and without hope. That can happen to us.
Pray for your cousin, that he may realize the seriousness of what's happened to him, and turn in faith to Christ. Ask God also to give you an opportunity to share your concern with him and urge him to face his need to put his trust and faith in Christ.
Make sure also of your own relationship with God. God loves you (just as He loves your cousin), and the most important decision you will ever make is your decision to give your life to Jesus Christ.