Well, "cutmeamango" does rearrange to "me a gt man c u. o!" His name, therefore, is code to suggest he is a prominent member of the GT development team, probably Kaz himself (he says he is a "a gt man" who knows something important will happen in two days, so he must be calling the shots over at PD). He says he can "c u", as in, "see you", which can be taken to mean he understands and appreciates your point of view that you are desperate for news. He responds to this concern, concluding the message with an "o!", which is most likely an expression of surprise, suggesting that there will be a surprise in two days, possibly the release of the GT Sport beta.
Cutmeamango is Kaz confirmed.