Based on lines 1-4 of "Remember," what can you conclude about the person being addressed by the speaker?

Well, this is an interesting question, especially stopping there. Start by being very clear: the poet does not say much directly about the person being addressed. It is all implied or communicated through the speaker discussing herself. Start with the first line—"Remember me when I am gone away." The person addressed is close enough to the speaker that she can ask him or her to remember after departure. The person addressed is also going to stay when the speaker leaves.
Go to the second line: "Gone far way into the silent land." The speaker is dying, or planning for death, and by implication, the person addressed is not. The person being addressed is either not ill or not old.
The third line reads, "When you can no more hold me by the hand." You would only say this to someone who took you by the hand, and repeatedly. These people are close. They might be lovers; they certainly love one another.
The final line "Nor I half turn to go yet turning stay" underscores this relationship. The speaker is close to the person addressed, drawn to them, and loves them.
https://www.poetryfoundation.org/poems/45000/remember-56d224509b7ae