The show is still selling a little on the slow side, so there's no guarantee that the Gallery would be open. I'm sure some performances will sell gallery seats within the next couple weeks. And, if it's a good review, then the gallery would almost certainly open.
Even Patti couldn't fill the gallery last summer. It was totally empty when I went on a Saturday last year. I can't imagine the underwhelming choice of Damn Yankees would fill it more. Guess they just want to pay fewer staff members, which is a shame because the rear mezzanine is oppressive in terms of leg room and unfortunate in terms of sight lines.