No once dlc is redeemed it is tied to your gamertag, you cannot give it away once redeemed. If you have still got the dlc in code form on a card and have "NOT" already redeemed said "CODE" you can give that card to your friend then he or she can redeem and
download it. If the GTA V game is in disc form you can give him or her the physical game. If the game is in digital form you cannot give it away as it is also tied to your gamertag (if downloaded from games on demand) If you installed the game from a disk
to a hard drive or USB stick it is tied to the physical game disk.
To put it simply if you wanna give your friend GTA V, give them the disk to keep. If the downloadable content is already redeemed you can't give it away. If GTA V is a games on demand version you cannot give it away either.