is there a minimal amount of entries to get cv?

Yes, i think its 5. You can find it in the FAQ :)

Public (non region restricted) = 1 (because without a entry you will not have a winner either).
Rest = 5

For free games it does not matter, since you won't get any, if you given more then 5 copies of something cv will diminish.
For public giveaways 1 entry will be enough, for groups,whitelist etc you need 5 minimum.

For your Turkey-locked giveaway u need 5 entries to get CV. Remember, winner have 7 days to accept your gift (could be a problem for some of people during holidays),
Your giveaway ends January 2 and coupon is valid till January 7. I suggest to you to recreate this giveaway and make it one week long (for example 10-17 December).
You can't use this coupon with others discounts so if dev will make discount on winter sale (like 10 or 20% :p) - u'll have a small problem xD