Depends on the context and what they dying person is afraid of about dying.

When my grandma was dying, she was worried about us. After we told her we'd be okay she went pretty quick. My aunt was worried about leaving work behind. Once she knew it was okay and we promised we'd take care of it and we were upset by it or anything, she went pretty quick too. My other grandma kept getting lost in time. Once we let her know that we'd wait for her while she went to find her mom & dad, she went pretty quick.

I think you have to address the fear, that's what needs to be okay.

We all know we're going to die. We all fear it. That fear comes out in different ways though.