If your intention is to make a near perfect copy, then the details on the faces could use some work. The large black contour line by gentleman's chin (which I'm guessing is the shoulder and part of the trifold behind him), and the red tip at the corner of the lady's hair catches the eye. Lastly the back ground comes off flat to me. I'm under the impression that this isn't finished work because the proportions look good and blending of colors are well done. So the aforementioned problem spots can be easily resolved. Other than than, it's impressive work.

This is looking great! I do think his head could be slightly bigger. So far I think you've done well on the faces, but maybe they need a little bit more detail if you have really small brush. I suggest trying to get a bit more definition in for the shape of the eyes. Right now, their faces look a little vague which, to me, puts less focus on them. Like making it seem like they are, figuratively speaking, a fading memory. For the background: at this point with how much detail you have in the background, I do suggest rendering it more. But, maybe you could put a thin wash over the gate thing to kinda fade it so it isn't super in focus; it is a little distracting. Or just blur the edges of it. Overall it's looking really good though!