A young man I know committed suicide. Someone remarked that if he was troubled that day, he is really troubled now because the Bible says he is in hell forever. Is this true? If so, can you give me Bible references to support it, likewise if it is false?
That is NOT what the Bible says. That's what a lot of people think, but God isn't one of them.
Trusting Christ is the only criterion for determining whether one goes to heaven or hell. If the young man had trusted Christ and committed suicide as the only way he could think of to make the pain stop, then he is with the Lord because of the security of the believer. For instance, Rom. 8:38-39 says,
"For I am convinced that neither death nor life, neither angels nor demons, nether the present nor the future, nor any powers, neither height nor depth, nor anything else in all creation, will be able to separate us from the love of God that is in Christ Jesus our Lord."
Nothing--including our own acts such as suicide--can separate believers (the context of Paul's letter) from God's love.
Consider also John 10: 28-19, which shows we are DOUBLY safe:
"I give them eternal life, and they shall never perish; no one can snatch them out of my hand. My Father, who has given them to me, is greater than all; no one can snatch them out of my Father's hand."
Not even ourselves.
If the young man had not trusted Christ, then unfortunately he is in hell, but not because of suicide: it would be because of his refusal to believe in and entrust himself to Jesus.
I hope this helps.