One who gates or closes with a gate; a person who installs or operates gates.
From 'gate' (verb, to provide with a gate) plus '-er' (agent suffix). This occupational word is less common than 'gatemaker' but carries the same root concept.
The verb 'to gate' is alive and well in modern speech—college campuses with 'gated' access employ digital gaters now instead of people, showing how an ancient job has evolved with technology.
Complete word intelligence in one call. Free tier — 50 lookups/day.