Paula,
Oh my goodness, this must be very hard for you to go through if someone has asked this or said this.
There are two viewpoints which need to be addressed. Let's go for the spiritual since that is the easiest one to address. Simply stated say what the Spirit is prompting you to say. I am not sure if this person believes as you do, but God knows the best things that this person needs to hear.
The second viewpoint is if you know this person is seriously considering suicide, have you considered getting help for them? If they have come out and told you that they are suicidal they need to be in a setting that is safe for them and will help them through this tought time. If they cannot stand up for themselves to get help, then please prayerfully consider what I am saying and to decide whether you need to pursue them getting help.
I speak these things as one who has struggled with suicide in my past. At that time, I did not want to hear about heaven or hell or any beliefs. I needed help. At the time I did not believe in God or heaven. And I know looking back if I knew that there was a heaven I would have gone and committed suicide. I really do not think that it would be beneficial in asnwering this person's questions. I would exhort you to talk one on one with this person and come up with some ways to solve this problem without resorting to suicide. If this cannot be met, then I would doubly exhort you to seek help for this person. Theology is not important here, a human life is at stake. There should be no peace about comitting suicide.
I am sorry if this is not the answer you are looking for but this is what is on my heart to say. I shall be praying for you and the person who is contemplating this. Be supportive of them but do not be sucked down in this emotional chaos.
Keep us updated on this one.
Sincerely,
Anne C. McGuire