The eruption north of Vatnajökull glacier will not affect air traffic to and from Keflavík International Airport unless it changes in character.
Icelandair press secretary Guðjón Arngrímsson talked to visir.is: “We don’t see this having any effect on our flights. At most there will be minor changes. This should not disturb international flights.” He encourages everyone to follow arrival and departure times (which can be seen here).
Scientists are in the eruption area and following what is happening. No plane will fly over the eruption until tomorrow morning after sunrise.