FILMCHAT: No, Noah is not Gnostic. (Say that ten times fast!) (Peter T. Chattaway). Chattaway's post is in response to a blog post by Dr. Brian Mattson, Sympathy For The Devil, which argues that the film is Gnostic.
I link to the discussion mainly because it includes some valuable background material on Aronofsky's interest in Kabbalah. (Incidentally, his first movie, Pi, is one of my favorites.)
As to whether Kabbalah is "Gnostic" or not, it really depends both on what you mean by Gnostic and which texts in the vast sea of Kabbalah you are talking about. If you take Gnosticism to mean a system of thought that assumes that the spiritual elite possess crucial secret knowledge that gives them salvation or supreme spiritual authority, then Kabbalah is pretty much Gnostic. If you take Gnosticism to mean a radically dualistic worldview in which the universe is a war zone between good spiritual forces of light and evil spiritual forces of darkness, then at least some Kabbalistic thought is Gnostic. But if by Gnosticism you mean acceptance of the demiurgic myth (that an evil or at least imperfect secondary creator, the demiurge, created our material world, and that this material world is fundamentally evil and must be escaped by the spiritual elite), then Kabbalah only plays with the idea.
One example of a rather Gnostic (in all three senses) Kabbalistic text is the Treatise on the Left Emanation, written by R. Isaac ben Jacob HaCohen in Castile in the 13th century. It has typically Gnostic-sounding emanations of spiritual beings, some good and some evil (with the main focus on the evil ones), and it includes a primordial threefold emanation of successive creations, each more evil than the last and each having to be destroyed. All that sounds pretty Gnostic, although there is no clear demiurge behind the preliminary evil creations, and they are distinguished from our world. But from what I know about Kabbalah, which is not all that much, this text has an untypically Gnostic inclination.
More on the Noah movie here and links.
UPDATE (3 April): The two bloggers noted at the beginning of this post have continued the discussion. See Chattaway's post for updates. And Loren Rosson weighs in against Mattson's claim about Gnosticism in Noah here. Be aware that there are lots of spoilers.