eBay updated its policies to prevent the "chaining" of gift cards, largely to combat fraud and money laundering.
The short answer is : you generally cannot use an eBay gift card to purchase other gift cards on eBay. ebay gift card buy other gift card
: If you attempt to use an eBay gift card for a restricted category, the card will simply not appear as a valid payment option during checkout, or you will receive an error message. Key Restrictions to Keep in Mind eBay updated its policies to prevent the "chaining"