I don't think the culture gain is that relevant to winning on Deity. My first game I've won with Scythia (didn't abuse the sell feature) and you just win in all fronts due to the sheer amount of cities you conquered. In my game I got assaulted by both brazil and sweden and a barb camp but I had prepped 3 slingers into archers into 2 saka horse archers which cleaned up everything. I got a catapult and destroyed sweden then upgraded to crossbowmen and took over brazil. I did get a great general, could be due to the fact that I had an encampment with stables. I was afraid what lied ahead as my military might was half as much as the enemies, turns out that mil might appears to just be the added str of everything so it's grossly favored towards people with mass warriors who just end up clogging anything that can hurt your units. After having 2 civs worth of cities I could do anything I want, but I focused on production into commerce and science and just kept on pressing for domination. Cavalry were good and being able to pump two at a time was really strong, but the real deal came in the form of 2x helicopters per one. I started mowing down cities by either artillery barrage followed by helicopter assault or bombing runs with again helicopters swooping in for the kill. I never abused the deals though that would have made some stuff easier at the start I guess. Gorgo might be worth it just to get the governments early, I imagine being the first fascist would make warring that much faster, but at that point the game is already won anyway.