New York and Pittsburgh are about 315 miles apart by road. Split the difference and you arrive near Philadelphia, the city closest to the halfway point between them. That puts roughly 2 hr 1 min of driving on the New York side and 5 hr 23 min on the Pittsburgh side — the fairest single meeting point among the cities near the middle.
That's a half-day drive from each side, so Philadelphia suits an overnight or a weekend rather than a quick coffee — long enough to want a reason to stay, short enough to drive.
If Philadelphia doesn't have what you're after, Washington and Buffalo are also close to the midpoint and worth a look — each keeps the drive reasonably balanced between New York and Pittsburgh.
City descriptions adapted from Wikipedia (CC BY-SA); photos via Wikimedia Commons, credited above.