Factorio only has very basic gates. slightly more advanced than plain redstone, but not anything close to command blocks.
There are three types of combinators: arithmetic, decider, and constant.
Signals have a channel name (one for each item type and a few dozen other options) and an integer value.
Arithmetic combinators can perform arithmetic operations on one or all signals with one signal and a constant integer, or two signals.
Decider combinators perform comparison operations.
Constant combinators emit constant signals on a given channel.
There are also abilities to detect state on some other items and cause behavior to change, the equivalent of observers, dispensers, pistons, etc.