Advice for adding pumpkin to pancakes?
The excellent answer to the question Why can applesauce be used in place of oil? points out that one of the key reasons for using applesauce in quick bread type recipes such as pancakes is the pectin.  Pumpkin also contains pectin.  Therefore pumpkin should provide a similar effect on your recipe as the applesauce.

What the pumpkin puree won't provide is the sugar that applesauce provides.  You will likely want to up the sugar provided by your recipe to account for this, unless you routinely use unsweetened applesauce.  The water content between pumpkin puree and applesauce will also be different, as will the exact proteins.

I would suggest starting with a one to one replacement of pumpkin for applesauce for a very pumpkin-y taste, but you will have to experiment.  You will also want to add sugar to taste.  If you want a more subtle flavor, consider substituting only part of the applesauce with pumpkin.