This is a good question that highlights some of the confusion about vocabulary that can come up when discussing gynaecomastia surgery!
The pectoralis muscles, the nipple and the areola are different things. In gynaecomastia surgery none of these tissues are removed - the aim is to leave all three intact. If any (or all) of them are removed they will not grow back, but nor will you look normal.
In gynaecomastia surgery the tissue that is removed is the fatty and/or glandular tissue that sits under the nipple and areola, on top of the pectoralis muscle.
It is possible for the fatty breast tissue to reaccumulate after gynaecomastia surgery if the patient undergoes significant weight gain. The breast glandular tissue does not regrow after excision.