Yes, but it must be someone who already has a right to live on the reserve.
To give reserve land to someone under a Will you must have the right to the land. This could be under a Certificate of Possession given by your First Nation or under Land Code rules if your First Nation has one. Unless your First Nation has a Land Code, your right to possess reserve land must be approved by the Minister of ISC for it to be valid.
Sometimes people are living on land that has not been allotted to them. This land would generally still belong to the First Nation, so the person living there could not give it away in their Will.
Whether or not you have a Will, a person who cannot live on the reserve cannot inherit the right to live on reserve land. If a person who cannot live on the reserve inherits reserve land, it is sold to the highest bidder who is allowed to live on the reserve. The money from the sale goes to the person who inherited the reserve land.
Even if the person can live on the reserve, the Minister of ISC must approve it before they can live there. If the First Nation has a Land Code the Minister’s approval is not needed.