If espionage is turned off, culture is pretty badly nerfed. It takes huge multiples of what it usually is for border pops and culture influence on tiles. It also makes culture victories almost undoable because it takes so much more to achieve it that some empire wins another victory first. I know because I don't like the espionage mechanism in BTS at all and enjoy putting culture pressure on my neighbors rather than going to war them . In the early days of BTS, I turned it off and discovered what happens to culture. It was long enough ago that I can't remember the actual numbers for what happens but it was bad enough that after one game, I never did it again. Putting up with the espionage mechanism was lots better than ruining the culture aspect of the game.