Well good luck -- I personally think that the shooters cited so far are not even close. One or two have photos that are evocative of some Gibson pics, particularly from around the "Quadrants" period, but that could almost be coincidence.
Get a hold of "Refractions" if you haven't -- Gibson also published a description of his 1970's methods in the Lustrum "Darkroom" books (hard to find, but some libraries have them).
The Gibson printing technique is currently pretty-well outside the range of digital, btw -- digital cameras block up the highlights. Scanning from over-dense negatives and getting an expanding range of tones is beyond the density-precision of most (if not all) scanners. You can do some with controlled lighting in the studio, but you'll still not get the reflected contrast into those sorts of ranges. So far, B&W film remains the way to go if that look is your desire.
Oh, another one is Mario Giacomelli. Moody and gritty, w/o the glamor and cleanliness of Gibson's subject matters.
Gritty? Dense? There is nobody else but John Max:
He makes Velvia photographers feel sorry they hurt their eyes on his work. And he's also brilliant.
Not sure if you'll find he looks like Gibson, though.
I'm sure there must be some NY dealer somewhere with his prints, and if you find anything over there, I would really love a little report! Even in Canada, where he worked for most of his life, he's pretty much unknown outside of artistic/academic circles. There has been no recent publications of his work since the early 80s. Some exhibition catalogues, but no proper reprints of his books. It's a shame.
It's the Velvet Underground syndrome: only 10 people saw his work, but the 10 were all photographers, and his influence is actually bigger than his popularity. He was buddy with Robert Frank, Leonard Cohen, Frank Zappa, Andy Warhol, and plenty of other people.
I'm surprised no one mentioned Bill Brandt. He is a one of Gibson's acknowledged influences.