Of course God has the ability to save a sinner after he is dead, but based on His Word we know that He does not for “as it is appointed unto men once to die, but after this the judgment.” Salvation is always of the Lord. (Jonah 2:9) He chose before the foundation of the earth whom He would save in Christ. (see Ephesians 1) Only those born again this side of eternity will be saved. (See John 3) “The salvation of the righteous is of the Lord.” (Psalm 37:39a)
So, we pray.