When I won rush lottery a few weeks ago during previews, it was for a standing room ticket. My understanding is rush winners are normally assigned the front row or standing room.
Once the door closes, an usher or someone from production assigned us to sit in empty seats in row D since there is no late entry.
From their Instagram post 2-3 days ago, they said day-of-cancellation line tix are available 90 mins before performance.