The thief is brought up by everyone who wishes to deny that obedience in baptism is necessary for salvation. Baptism puts us in Christ - Galatians 3:27. We are baptized into his death - Romans 6:3. How can one be saved outside of Christ? How can one be saved by the blood if he has not had contact with His death?
First, as you request, a direct response, yes the thief was saved.
John came baptizing in the wilderness and preaching a baptism of repentance for the remission of sins. Then all the land of Judea, and those from Jerusalem, went out to him and were all baptized by him in the Jordan River, confessing their sins.
Therefore, when the Lord knew that the Pharisees had heard that Jesus made and baptized more disciples than John (though Jesus Himself did not baptize, but His disciples), He left Judea and departed again to Galilee
"Behold, the days are coming," says the Lord, "when I will make a new covenant with the house of Israel and with the house of Judah-- not according to the covenant that I made with their fathers in the day that I took them by the hand to lead them out of the land of Egypt, My covenant which they broke, though I was a husband to them, says the Lord. But this is the covenant that I will make with the house of Israel after those days," says the Lord: "I will put My law in their minds, and write it on their hearts; and I will be their God, and they shall be My people. No more shall every man teach his neighbor, and every man his brother, saying, `Know the Lord,' for they all shall know Me, from the least of them to the greatest of them, says the Lord. For I will forgive their iniquity, and their sin I will remember no more."
And you, being dead in your trespasses and the uncircumcision of your flesh, He has made alive together with Him, having forgiven you all trespasses, having wiped out the handwriting of requirements that was against us, which was contrary to us. And He has taken it out of the way, having nailed it to the cross.
But they have not all obeyed the gospel. For Isaiah says, "Lord, who has believed our report?"
Do you not know that to whom you present yourselves slaves to obey, you are that one's slaves whom you obey, whether of sin leading to death, or of obedience leading to righteousness? 17 But God be thanked that though you were slaves of sin, yet you obeyed from the heart that form of doctrine to which you were delivered. 18 And having been set free from sin, you became slaves of righteousness.