If you receive a Vanilla eGift Card, you should know that the link to the page with your eGift card details will expire after some weeks. The link can supposedly be reissued, but it must be requested by the person who purchased you the eGift card over the phone. So, best to save the card details somewhere once you receive them.
The eGift Card funds are advertised as never expiring. It's not clear to me if that guarantee holds for funds left inactive for a long period of time.