well, i support your views man!
to be fair on her part, if she still insist that it was hers
try asking for a painting process! that would be the verdict!
i know a lot of great artist (in real life and over the net) who can do something like her, but most of them use traditional art like colored pencils and watercolors, so i'm pretty sure it was pure talent haha so i'm not really good in telling what's what in digital paintings
well, that's just a suggestion