Drawn through gate during an Arkham encounter
Delayed has no bearing on whether an investigator has an Other World encounter or not.
However the gate takes precedence.  Both investigators should have been drawn through the gate first, then the monster appears.
From the Dunwich Horror FAQ:

Q: When a location card says a gate and a monster appear, which appearance is resolved first?
A: The gate appears first, and any investigators at the location are drawn through the gate. Then the monster appears. Monsters that appear as a result of these encounters stay on the board, count against the monster limit, can go to the Outskirts, etc., as normal.

And from the errata section of the same document:

Arkham Encounters
(pages 8-9 in the first printing of the Arkham Horror rules)
If an investigator is drawn through a gate that appears as
a result of an encounter (such as “A gate appears!” or “A
gate and a monster appear!”), then he is delayed, just as if
he had been drawn through a gate in the Mythos Phase.