They had technical input, this doesn't point in anyway to the LM project though.
Their is a reason why most LMP look pretty similar, because the shape is defined by a combination of packaging, crash safety, technical regulations, reliability/survivability, efficiency and aerodynamics. Unless Nissan do something radical like a Front engined LMP, I honestly can't see it being that different.
I still think people are looking for a link that isn't there. In my opinion, Nissan Marketing asked Nissan Design to get some young designers to design a car for a video game, with the the brief 'what might the GT-R look like in the future', they did it, and the technical guys had a quick look to make sure they designed something that had a grounding in reality. But, I could be also be wrong on that.