Of course you can, using the standard zoom +- keys.
Note that, on a Quick Pushback (opposite to the full editor), the airplane position is not changed (it would kill the immersion factor), so the default view used, which is the Top-Down view, will still be centered on your airplane, so zooming in won't help very much to see the pushback destination more clearly.
But here the GSX custom camera system can help. If you right-click on screen, select a "Custom" camera and choose the "TOP FSDT Editor camera", the view will now be centered on the object currently selected for editing, which in this case it's the either the pushback final position or the intermediate Corner node, and this one can be also zoomed in/out with the +- keys, to set the final point more precisely.
This is also valid in the full customization editor, so you can use that camera to precisely position any vehicle, or the Docking System (very useful for it), or a jetway.
