Yes. We learn from our Lord's own words that Judas was guilty. Matthew 26:24 and Mark 14:21 both state, “The Son of Man will go just as it is written about him. But woe to that man who betrays the Son of Man! It would be better for him if he had not been born.” Matthew adds (verse 25), “Then Judas, the one who would betray him, said, ‘Surely, not I, Rabbi?’ Jesus answered, ‘Yes, it is you.’ ”
Apparently Judas had played the part of a good disciple, and when our Lord first announced that someone would betray Him, none of the other disciples seemed to suspect Judas. Each gospel records their surprise and confusion. (Matthew 26:21,22; Mark 14:18,19; Luke 22:22,23; and John 13:21,22)
Matthew 26:24 (quoted earlier) tells us two things: 1) Jesus knew he would be betrayed and by whom. 2) He warns the potential evildoer about the dire consequences and gives him a chance to change his mind. Verse 25 shows the deceitfulness of Judas, who continues to play the part of an innocent disciple.
Yes, Judas repented when he saw Jesus was condemned, and he even attempted to return the 30 pieces of silver (Matthew 27:3-5). Maybe Judas wanted Jesus to be “only” arrested and humiliated, not sentenced to death. (We know Jesus had warned his disciples of His impending death, but “they did not understand what he meant…”
Whatever the reason Judas had for getting Jesus arrested, it showed his hardness of heart and deceitful nature. How could a person spend over three years of his life with Jesus Christ and not be touched by His righteousness, unselfishness devotion to His Heavenly Father, and love for all mankind?! How could Judas want to harm someone so pure and loving?
Whether this sin merits eternal death is up to God. But Judas’ guilt is certain. As Jesus told Pilate: “…the one who handed me over to you is guilty of a greater sin” (John 19:11).