***** NOT A TEACHER *****
(1) Without knowing anything else besides the paragraph that you have
given us, I would get this impression:
SAIC is a big company (gorillas are big) that is not well known
(it is hidden by the mist, that word meaning something like "fog").
In other words, American Airlines is well-known, but most people
are ignorant about SAIC's huge size and huge income because it
is like a gorilla in the mist (that you cannot see very well).
(2) I googled after reading your question and found two important
(a) There was a 1988 motion picture called "Gorilllas in the Mist"
about Ms. Dian Fossey, who spent her life studying gorillas in
Africa. (or: Dianne)
(b) I learned something that I had never known (of course, I do
not know MOST things!!!):
Some rude people here in the United States have used that term
to refer to a certain group of people in this country.
(a) The newspaper (?) that published that article used that
term innocently, I'm sure.
(b) It would probably be a good idea (a VERY good idea) NOT to
use that term, for you could accidentally offend some people.