It's not a controversial claim from a psychology standpoint, at least if by 'rape fantasy' you mean an erotic fantasy of being overpowered sexually/had sex with against one's will ('one' in this case may or may not mean the actual woman doing the fantasizing, as some people fantasize about characters other than themselves). You'll need access to an academic database to read them, but in just a few minutes of keyword searching through some of our psychology databases here I found studies addressing this topic from Zurbriggen & Yost; Bond & Mosher; Strassberg & Lockerd; Pelletier & Herold; and Knafo & Jaffe. I glanced at only the summaries for these; the latter three all found more than half the female subjects reporting fantasies of this type. The Zurbriggen & Yost one looked interesting because it addressed the fact that having such fantasies is not correlated with attitudes about real-life rape. That fits with what I remember learning about this topic when it was briefly covered in a psychology course I took as an undergrad, which is that the prevalence of these kinds of fantasies is commonly explained as a way of enjoying the idea of inspiring uncontrollable desire, without the real-life experience of being humiliated by having no control over the situation.
But I don't know that any of that is really relevant to the ad. I find it creepy and weirdly emotionless, as if they couldn't quite decide whether they more wanted 'drama' or just another artsy mishmash of beautiful oiled bodies lounging nonchalantly around. I wouldn't say it suggests that women enjoy being raped, people do all kinds of things that no one would actually enjoy in fashion ads, but it's certainly more unsettling than most. D&G claimed their aesthetic inspiration for this ad was 'Napoleonic' (early 19th cen. French) art, I suppose meaning people like Delacroix, Ingres, etc. who commonly painted densely peopled (and in Delacroix's case, often violent), narrative scenes with naked or seminaked women, iconic or 'realistic,' draped about the foreground. Generally I find it a bit grandiose when advertisers describe their work in that way, but then fashion designers do often see themselves as artists, so perhaps it's not so strange.
Spain actually has a law against depicting women's bodies in advertising in a way that's 'irrelevant' to the product, which strikes me as pretty extreme, but I guess that's why this ad first ran into major trouble there. I find it interesting that it ran in women's magazines in Italy, but in a men's magazine here. In any case, the ad's been pulled now in response to all the complaints, so end of story, I guess.