2 weeks since a :/

contact support to mark as received if its in his/her library

Has he/she been online this past 2 weeks ?

Also did you mby try adding him/her on steam ... and asking him if mby there is an issue ( like its a region lock or some other issue )

Other then that you can contact support , and ask them to add feedback for the GA if he/she has the game activated in his/her account .

Check his Steam library - if he has activated the game, send in a support ticket for "Request Received Feedback."
If he has not activated the game, try contacting him - either on Steam or in an old giveaway of his, to ask why.

half solved! support will reroll way easier for me the game to another, since the winner already had the game won.