I just ran through it and it worked fine. This is how I went about it doing this.
In the Admin site I went to Configuration > Payment > Gift card management. Then clicked 'Add New'... In the 'Purchased by Customer ID' I put my CustomerID number. Then I selected email and emailed the gift card to another user in the office.
They added an item to the cart, pasted the serial number that was emailed to them and I noticed the amount didnt get taken off until right before checkout, it wasn't instant like adding a coupon.
If you tried this let me know, I'll help think of other ideas.
SQL 2008, Visual Studio 2010
Source: C#
Version: AspDotNetStorefront ML 8.0.1.1/8.0.1.1
Framework: .Net 4.0 (Running)