I am not quite sure what you are looking for. The vast majority of people spent a rather short time in the camps, anything over three years being extremely exceptional, so it wasn't as if they had been cut off from the world for decades. Also, news did reach them through various means, from rumours to scraps of newspaper. As to them realising what they had gone through: they were the ones that realised the enormity of it, it was the outside world that needed telling, and the survivors sometimes found it hard to get the world to believe them as the scale of the atrocities was quite unprecedented.

Ruth Kluger's autobiography Still Alive includes her and her motber's escape from a death camp to a work outfit, and their eventual abscontion from that. As I recall, while they had somewhat limited access to news, they were aware of the general deterioration of Germany's military situation. It was also quite clear to them that a genocide was taking place. "Death," she said at one point, "was all around me." She also described one of the camps she stayed at as the "stable that fed the slaughterhouse."