If I accept gift cards from a restaurant as part of their payment and then give them away as public relations - do I need to classify the gift cards as cash or as trade?

Your question is not as clear as it could be. Do you work there? I don't understand the 'as part of their payment' part. However, a gift card is used just like cash. If I pay with my debit card the money is taken from my bank account. When you buy something with a gift card, the money has already been paid the card is just how you redeem it. I hope this is clear and I hope it helps.