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The structure of xenon fluoride is a capped octahedron. The lone pair is stereochemically active, i.e. it will rotate about.
The dipole moments of the axial fluorides will get cancelled, and so will those of the four equatorial fluorides will also cancel each other. Thus, overall, the molecule should be nonpolar.
But what effect will the stereochemically active lone pair have on the polarity? Will the polarity keep on changing?
First of all, the point group for $\ce{XeF6}$ is disputed. The latest I saw was $C_\mathrm{3v}$, not $O_\mathrm h$ but the $O_\mathrm h$ is so energetically close to its $C_\mathrm{3v}$ that it is likely in a perpetual state of transition between the two. As for polarity, due to this it is hard to think it would have a permanent dipole. One would assume it would be easy to induce one, though.
$\ce{XeF6}$ is not the typical molecule the different models were made for, so YMMV.
