Are gifted data taken from the ones that are the more close to expire?

ChaoticFel Yes. You can gift any unused data when you’re near the end of your payment cycle. You can only gift data from your current payment cycle, and it must be gifted before your payment cycle ends (before your data rolls over). How do I know when my rolled over data will expire?
Each batch of rolled over data will expire after two (2) complete payment cycles, and this even if you change your plan.

To see when a Rollover will expire:

Go to My Plans in your Fizz account.
Under the plan you wish to view (if you have more than one) click on See Usage.
https://fizz.ca/en/faq/what-is-rollover-and-how-does-it-work