I received a gift card to a mall I probably would not have shopped at if I hadn’t received the gift card… am I obligated to tithe 10% maaser to from the gift card received?
It is proper to give maaser from the amount of the gift card.
A number of authorities, including the Chazon Ish (as cited in Derech Emunah, Matnos Ani’im 7:27), rule that there is no obligation of separating maaser for gifts of goods or properties.
Rav Shmuel Wosner shlita notes that this is the common custom (Shevet Halevi, vol. 5, no. 133, sec. 7).
However, concerning gift cards there is room to argue that on account of its purchasing power a gift card is like money, and therefore one should give maaser from it.
This is the ruling given by Rav Nissim Karelitz shlita (Chut Shani, Yom Tov and Chol Hamoed, p. 351), who writes that if one receives supermarket vouchers that can be used for buying many different products, the obligation of separating maaser applies.