Most likely.... all day long you hear of leopards killing gorillas regardless if it were ambush, since how many ambushes have leopards kill male lions, the animal he co-exist with more than any other predator?
Zero.
But it would be interesting to see how a single gorilla would defend himself against a lion, gorillas if shown a pic by himself would look opposing, but if he was next to a lion, he'd look rather small, since the lion is heavier on average and at max ranging from 100-200 pounds, also when on all fours the lion is taller by a foot and a half, toppled with if the gorilla stands on two feet he'd be 4-6 feet tall while the lion on his hind quarters would be 7-9 feet tall. Not to mention the lion has a mane that increases his mass by 20% on average and 50% at max, so in reality a gorilla will look half the size of the lion.
Gorillas wouldn't work together no matter what the occaison calls for, if there was a elephant vs 50 gorillas in there conflicting teritorys, they wouldn't attempt to work together and bring the mammoth down, yet small prides have been documented taking down even bull elephants.
No support/evidence shows that gorillas team up in large groups, at best maybe two matriachs or a pair of mates male/female will aid the other if its attacked, but any larger numbers and the gorillas wil be more prone/suspect to attack his own species than go after a superior predator. In fact no evidence is on hand to support the gorillas fighting capabilitys, just King kong fans thinking Fictional=Reality when comparing Kong vs Real Gorilla, they don't shatter bones, break limbs, necks, backs ect...even if some one can show a abstract (Which no one can) the lions bone density is just as hard/dense at ratio 1.28 as alaskan brown bears, so if any ones bones is being broken and or shattered its going to be the gorillas.
Most likely they will occaisionally fight until exaughsted or killed, and day by day the scenario will repeat, 1 by 1 the lion can win even 2 on one.
Since the lion has:
-Bigger canines fangs and mollars for a more devastating and effective bite.
-Bigger skulls for a more potent and stronger bite pressure.
-Is acustom to killing larger animals by 2-8x the gorillas size rutinely, even alone.
-Is Stronger in the frontal quarters having bigger, taller, longer, broader shoulders for better wrestling/grappling.
-Has Razor sharp claws/20 that can rip/tear skin like paper and cause shock to nerves paralyzing animals by pure pain.
-Is faster in dexterity, agility and pure speed.
-Has better acrobatics, manuverability and movements + skill in combat.
-Fights more often, more fighting=more fighting experince=better fighter
-Is an expert at killing and is a carnivore which tends to be prone to need to kill.
The gorilla is...
-Semi strong yet weaker than his oppenent the lion, even leopards have torn off gorilla arms in captivity.
-Diet consist of 90% vegatation=no conditioning as hunters/predators have.
-Hardly ever fights (Little to no documentation of them to show physical contact)
-Loses constantly to the lions kin (leopards) while lions don't lose to any ape/monkey/chimp.
-Quite slow due to his physiology
In terms increasing the amount of gorillas isn't going to increase the sucsses rate of killing the lion, a better scenario that gives the gorillas a chance is of a group housing 3 males 2 females and the rest there offsprings, a motivation to protect there children/family will be alot better than 10 males who would be more so determined to attack the other than the lion in a cage thats only 50 feet as its radius would automatcially have gorillas going for there kins throats on site, since the stress from that much tention will be a major factor.
If it were of the smaller cats, puma, leopard, jaguar ect, they would more have the will to oppose individual wise and have alot of other advantages, but against a lion or tiger, the scene the OP/TS layed down is just laughable, since over welhming them comes with a inctinct too do so, like wolves, wild dogs, hyena ect, a instinct the gorilla doesn't have.
Most likely this fight will end almost all the time like this:
A Raging lion and a gorilla with the ape in a bloody mess screaming in terror with mariah carey high pitch tones. lol