Cezanne had a major influence on Gorky’s development as we see with the consideration of spatial planes in this painting. Gorky is not emulating Cezanne, he is applying his consideration of planes in space, as we saw in the post of Matisse’s painting The Italian Woman.
Here we can see the consideration at the figure`s left shoulder. Note how the background feels like it is cutting into the shoulder. Or a better way to put it is the figure is in the space. We can see it in the other arm as well . The lower arm feels to be in front of the figure. The background coloured shape between the forearm and the shoulder reads as the space. Do you feel it?
There is a grey rectangle in front of the chair. What is it? It is not an identifiable thing, rather it is a plane in front, which is far better than showing the back leg of the chair. That evidence of perspective would be in conflict. Very impressive.