Comment on Chick-fil-A Copycat Chicken Sandwiches by John.
While pickle juice brine may not be part of the original Chick Fil A recipe, I have used it with very good results on several occasions. The pickle brine adds a very nice subtle flavor element to the breaded fillet and enhances the moisture of the finished product. My wife and kids(who are pretty picky) were very happy with the results. Give it a try!