Thanks for sorting out the places I had problems.
Þeir Ásgautur og Þórólfur voru komnir í svo mikinn klofa
They, Ásgautr and Þórolfr were (had) come into such a great straights
(ie in a tight-spot (metaphorical here, I think), were caught in a trap,
see klofa, Z1),
báðum megin en gengin (ganga) upp
both sides but (and the river was) swollen-with-ice (see ganga upp, Z15)
sýndist (sýnast) þeim áin óyfirfærileg (úyfirfæriligr).
the-river seemed to them impassable (not-over-convey-able).
allra manna gisting.
accomodation for all men (persons).