I would test each switch one by one and see if the look alike above them is an indicator about the light, in the case it is, then the one switch that activate the indicator reveal that it controls the light.
In the case were more than one activates the indicator, then the indicator must show something else, or there's 2 lights, which doesn't sound right. So the light switch would be the one that doesn't activate the indicator.
If none of the switch activate the indicator, then the indicator would be an occupation indicator that activate when someone is in, then there's no way to know if it's not written next to them and hidden by the PoV of the picture.
Gameworld: US-103 Broadway