Who here would be willing to die for something they know is a lie? I sure wouldn't...
It is not so important how the apostles died. What is important is the fact that they were all willing to die for their faith. If Jesus had not been resurrected, the disciples would have known it. People will not die for something they know to be a lie. The fact that all of the apostles were willing to die horrible deaths, refusing to renounce their faith in Christ, is tremendous evidence that they had truly witnessed the resurrection of Jesus Christ.
https://www.gotquestions.org/apostles-die.html

It is not so important how the apostles died. What is important is the fact that they were all willing to die for their faith. If Jesus had not been resurrected, the disciples would have known it. People will not die for something they know to be a lie. The fact that all of the apostles were willing to die horrible deaths, refusing to renounce their faith in Christ, is tremendous evidence that they had truly witnessed the resurrection of Jesus Christ.
https://www.gotquestions.org/apostles-die.html