WWE Network features a listing for "WWE Main Event Live" in the Tuesday 7 PM ET timeslot. You can view a screen capture below:
">@WWENetwork Tuesday at 7 PM. This is when they'll tape in Detroit pic.twitter.com/N1G35X7T7P
— Richard Gray (@wnwdotcom) March 3, 2014
While the date says "3/3/14," which is Monday, the speculation is this week's episode of WWE Main Event will air live on WWE Network before it airs from tape on Ion Television. The company normally tapes Main Event before Smackdown on Tuesdays although I guess it's possible they could tape it Monday before Raw. However, the assumption is the taping will air live on Tuesday night.
We'll see if WWE addresses it further during this week's Raw broadcast live on the USA Network.