1 plan without data and the other plan with 10gig data. will i be able to gift the other line 5 gig?

No. You can't gift data to a plan with no data.

Positive. See the link below. I also tried to gift my wife's plan that has no data and couldn't.
https://fizz.ca/en/faq/what-is-data-gifting-and-how-does-it-work
You cannot send a data gift to:
People who are not Fizz members
Fizz members with no data plan
Fizz members who have designated themselves incognito