The short answer is yes they can survive, but will do MUCH better indoors IMO.
I've always kept mine inside so I really can't offer any real world experience there. Having them indoors or at least at night affords you the luxury of bonding with them in a way not possible IMO vs 100% outdoors. I realize for some that is not possible, but you truly will be missing out by not having them indoors interacting with the family members.
That said...a GSP will lack a serious coat for real cold temps, yes if they are raised outdoors they will develop a heavier coat, but it will be nothing compared to say a lab. A well insulated dog house combined with a kennel run that is sheltered from the wind would be the bare minimum. You will also have to increase their food rations by up to 50% in many cases for them to maintain weight in cold temps.
My .02