I'm actually not sure I would use either one in your context. I might say something like
In Japanese train stations / On Japanese train platforms, floor markings ...
... guide / direct passengers to the correct location for boarding.
... show passengers where to walk and where to stand.
(If that's what you mean. It might help to know exactly what the floor markings say.)
(I would use 'marker' for a physical object like a reflective disc by the side of the road, but 'marking' for text or arrows painted on the floor.)
I would use 'influence' in subjective contexts where people have to make a decision or a choice that involves opinion or belief. E.g., 'Political advertising may influence voters.'
I would use 'affect' in objective contexts where an external force causes an empirically observable change. E.g., 'Climate change may affect the intensity of storms.'