Only those who hold to the truth and know what it means to be Born Again. John 3:1-21 After the Rapture it will be those who reject the mark and stand firm even unto death during the 7 year tribulation. He who endures to the end shall be Saved. Matt. 24:4-28
The bible does not tell us any certain number but it does say there will be less than most people think.
13 “Enter by the narrow gate; for wide is the gate and broad is the way that leads to destruction, and there are many who go in by it. 14 Because narrow is the gate and difficult is the way which leads to life, and there are few who find it.
The Bible gives no specific answer, at Matthew 24:13 it says, "But he that has endured to the end is the one that will be saved." How though can we endure to the end? At John 17:3 it says, "This means everlasting life, their taking in knowledge of you, the only true God, and of the one whom you sent forth, Jesus Christ." We first need to take in knowledge of Jesus Christ and apply his teachings in our lives. I hope this helps!