It seems to be the stuff of debate. Please see this LINK to help determine the case. It gives this quote from Journal of Accountancy.
"The IRS has not given guidance on how distributions from Sec. 529 plans affect the support tests. These distributions can be substantial. If the distribution is counted as support provided by the beneficiary (child), it could prevent the child from qualifying as a dependent. Sec. 529 plans allow the owner (usually a parent or grandparent) to change the beneficiary. This provides some support for the argument that Sec. 529 plan distributions should count as support from the account owner and not count as support provided by the child, but tax practitioners are still waiting for a definitive answer from the IRS."
