Digging the topic:
AI does "cheat" in numerous way.
Knows every tile on the map, knows units on that tile. Know if the tile is a city or how much defense would provide. Knows how many cities are on your turf.
Knows production in yer city, knows happy faces, health.
Basically AI knows everything.
It doesn't use the info in some cases though that would be deemed blatant cheating.
AI doesn't follow strategy in general. It has some "kind" of strategy in mind but not real one. Or at least far from what human may think of.
So the info is use when find 'bestXXXAction' is considered.
In the end: I don't know if that'd be qualified cheating. It's how the AI was designed. Like the developers told it's more a tile-base game than turn based one.
Everything revolves around the 'tiles'.