The problem with this comic is that the term gaslighting has nothing to do with that defunct profession: it comes from the 1938 theater play Gas Light, in which the dimming of the lights every night causes the woman to doubt her own sanity:

Jack goes to the flat each night to search for the jewels, and lighting the apartment’s gas lights causes the lights to dim in the rest of the building. His footsteps in the supposedly empty apartment persuade Bella that she is “hearing things”.