All you need for this glitch is two controllers and two Xbox profiles.

Step 1: Load up the game and press start on the second controller to bring the second character (the mule) into the game.

Step 2: Using your main character, face the mule and press LB. This will bring you into the gift chamber. Go to the gold pedestal and click on it.

Step 3: The screen will show loading then you'll be able to gift. Max out the gift amount and accept. Repeat this until you show 0 current gold. When finished press B.

Step 4: Use your mule character now and press start. This will take you to the sanctuary. Go over to the gift shelf and begin rejecting all gifts. When finished press B.

Step 5: Either press the down arrow on your main char or the mule to disconnect the mule character. Then press start to go to the sanctuary. Go to the gift shelf and accept all the gifts. You now have at least doubled your previous amount of gold.

A couple of notes:

-There appears to be no max.
-Once i hit 700k when I gifted gold it wouldn't subtract from my 700k. This made it really easy to go from 700k to 2mil
-The gift shelf will hold the previous amounts on the shelf, and it appears that it can only que up a certain amount. I suggest once hitting around 700k to just do 100k gifts 3x
-100k is the max you can gift in one chunk.