I'd be shocked if that were the case. I drive by there every afternoon on my way home, and have seen barely a fraction of the people at the patch. There were maybe a dozen people milling around inside today, where there were typically over a hundred. In prior years, they would have lines out the door at all times of the day with people buying pumpkins. This year, I walked in and was the only one in line, on the day before Halloween.
So I think a more apt comparison is that they're now making $70/family from 100 families (due to the cover charge), rather than making $50/family from 500 families, since so many just turned around and left instead of paying the admission fee. It would be like WalMart deciding to charge people $5 just to come in the door. Most people (like me) would simply go to the Target down the street and get the same thing.
Maybe I'm wrong and the decision has been a good one for them, but that would be very surprising.