What do you mean by "on the path"? Is he Buddhist or Christian? It really depends a lot on who this person is and the details you gave are too vague.
If he is a stubborn atheist or doesn't like religion, it's unlikely anything you could say or do would be helpful.
If he's a Jew, Christian or Muslim, you should talk to him on his own terms: tell him that God is all-loving and all-forgiving, that the important thing is to have faith in God, and that death is not the end, only another beginning. And that although he may be afraid, he can look forward to being free of the pain he's in right now and experiencing God's grace. Tell him that during the death process, he can find strength from angels God sends, to ease his pain during the process.
If he is interested in a more Buddhist perspective, I would say: Tell him to face death with the attitude of profound universal love (boundless love for oneself and others) and fearlessness. Tell him, in his last 3 months, to focus on the four brahmaviharas:
- Lovingkindness -- through being friendly and kind to others, or at least focusing on it mentally
- Sympathetic Joy -- through making others happy, being appreciative, being joyful in their positive mental qualities, including being happy for their happiness
- Compassion -- through being helpful to others, in any way he can, or in his case, trying not to be a burden
- Equanimity -- through not being for or against anything, not desiring death or fearing it, not desiring life or being afraid to lose it.
If he could maintain just half of those four qualities consistently for the 7 days leading up to his death, he would be assured that he would be reborn in a wonderful heaven.
Also, tell him to look for a kind of happiness that is independent of the circumstances he's in right now. He could find this place by thinking about all the good things he has done in his life, all the people he has loved and who have loved him.