Certainly with BA the minimum crew is 7 as D3R can be a self-help exit. At the same time, this door is an "overwing" style door and does not require mode selection.
I would have thought that, had the door been a normal door then you would need eight crew. I certainly wasn't aware that Boeing built 767-300s with four full-sized doors on each side, and I like to think that I know my aircraft (though the 767 is not one I'm particularly knowledgable about).