The character of Judas was, admittedly, less than stellar. He regularly stole from the money given to Jesus in support of his ministry (John 12:3 - 6, 13:29). He was greedy, deceitful and known to lie (Matthew 26:14 - 15). He also maintained an elevated opinion of himself and his importance among the disciples.
The Lord taught, for example, that his disciples should not choose for themselves the best seats at special gatherings lest they be humbled (Luke 14:8 - 11). As host of his last Passover, he had the right, but apparently did not exercise it, to determine who sat next to him in the most honored position. Judas, seizing the opportunity, claimed the honored seat at Passover for himself. This act of vanity, however, quickly backfired. He sat close enough to Jesus to be marked, with the "sop," as his betrayer to both John and Peter (Matthew 26:23 - 25).
Hope for the Hopeless
In spite of the above, there are mitigating factors that could lend themselves to Judas receiving mercy rather than the death penalty on Judgment Day.
Motivation
Greed was certainly one motivating factor for Judas to betray Jesus (Matthew 26:14 - 16, Luke 22:3 - 6). His goal, however, was not to have the Lord killed. Note how he responded when the devil (who DID want to kill Christ) left him and he understood the ramifications of his actions.
Now when Judas, who had betrayed Him, saw that He (Jesus) was condemned, he changed his mind and returned the thirty pieces of silver to the chief priests and the elders, saying, "I have sinned and have betrayed innocent blood" (Matthew 27:3 - 4, HBFV throughout).
The betrayer changed his mind, rejected the blood money, and admitted his guilt after learning Christ would be put to death. This outcome was not what he expected or wanted. His response is in stark contrast to many of the Jews and religious leaders in Jerusalem.
The Jews had been conspiring, for almost two years, to kill our Savior (Mark 3:6, Luke 6:11, John 5:18, 8:37, 40, Matthew 26:4). They not only were pleased to see him arrested and convicted, they openly mocked him while he was being crucified (Matthew 27:39 - 43).
Innocence and Guilt
Judas, after the controlling influence of the devil left him, came to his senses. He openly admitted that Jesus was completely innocent and did not deserve the death penalty. He additionally acknowledged he had sinned and proved that repentance by giving back the blood money. His mourning of Jesus' fate, coupled with self-hate for what he caused, led him to commit suicide.
And after throwing down the pieces of silver in the temple, he went out and hanged himself (Matthew 27:5).
Role of the Devil
Luke reveals that Satan, the day before the last Passover, possessed Judas for a short time (Luke 22:3 - 6, John 13:2). The devil then moved him to visit the chief priests at the temple to discuss the best time and means to arrest Christ in the quickest and quietest way possible. The next day he possessed him again, during the Passover, to finalize the betrayal by having the Lord arrested in Gethsemane (John 13:2).
Why was the devil involved at all? Wasn't Judas enough of a sketchy, self-seeking character to insure he would betray someone? The simple answer is no. He was not sealed evil like Satan. While the possibility existed that, at any point, he could decide not to betray the Lord, the Tempter was 100% guaranteed to sin. The betrayal, suffering and death of Christ, in fulfillment of countless prophecies, absolutely required the active participation of the universe's first and greatest sinner.
It Had to be Someone
Jesus knew from the beginning that someone would have to betray him to fulfill prophecy (Psalm 41:9, Zechariah 11:12). He and God the Father therefore had to select someone based on their questionable character and weaknesses (John 6:70 - 71). This someone ended up being Judas. They also knew that their greatest enemy would have to be allowed to manipulate and bring him down, something they would not allow him to do to the other eleven disciples (Luke 22:31 - 32).
Additionally, it should be noted that Jesus could have, but did not, personally warn Judas about the unique spiritual threats that would come his way. He did, however, warn Peter about being manipulated by Satan (Mark 8:33). He also warned Peter in particular, and his disciples in general, that the devil wanted to bring them down (Luke 22:31 - 32).
Conclusion
There is possible hope for Judas. His eternal fate is, of course, in the hands of God who knows the hearts and minds of all humans. He is responsible for his choices concerning Jesus' death but only to a point.
Rather than being a clear case where eternal spiritual death is justified, the mitigating circumstances of the actions of Judas offers hope he will receive mercy and redemption on Judgment Day.