A 1st level hobgoblin has +2 to grapple. If 8 hobgoblins tried to grapple Belkar at the same time, one would roll, and 7 others would use the "aid another" action. They need to roll a 10 on the grapple check to grant the +2 bonus, for which they have a 65% chance; in other words, the average bonus they'd provide is +9 (+2 x 7 x 0.65), for a total grapple modifier of +11.
On the other hand, Belkar is small (-4), but he has something like 11 levels of ranger (+11) and at least one level of barbarian (+1), and he was shown in previous comics to be fairly strong for a halfling (so, at least a Str 10... if not more). When he rages, he gets another +2 from Str increase, for a total of +10. They'd be evenly matched, but Belkar uses light weapons, so he'd be able to stab hobgoblins while grappled, whereasthey wouldn't be able to do much of anything to him (he has a lot of hp).