No evidence for resurrection. I do believe we have evidence for the Holy Spirit, though, which I don't think we can attribute to mass psychosis.
No proof of anything, even Jesus' existence. Only evidence, unless we can separate him from the Holy Spirit.
The story of Jesus was apparently transcribed after the facts of the New Testament narrative, or the destruction of Jerusalem and the temple, i.e., the end of the age. It seems a way for the Jews to have explained away their demise.
But then Paul and those he corresponds with also discus this looming world-changing calamity. And Paul's existence isn't really disputed. So it lends credence to Jesus' words. But amazingly, Jesus talks about this long before other Jews do. Long before tensions between the Jews and Romans reach a fever pitch.
Does that mean anything definitive?
What it means for me is that we have no reason not to believe him, especially considering the profound and widespread effects on the earth's landscape that he and the Holy Spirit have had.