The gifts known to the Forsaken are not the only gifts in existance! In fact, the truth is much to the contrary.
The existing gift lists are not "complete", but instead have additional secrets that can be pulled from the spirits, much like the Elemental gift list is said to contain the lores of all four elements. In addition, individual werewolves or packs sometimes learn strange and unusual gifts from spirits, and some lodges hold mystical secrets in reserve for their members. Lastly, of course, there are the Gifts of the Pure.
Also, check out Rituals