What would Arcane Sight tell you about something under invisibility?
It was confirmed/answered here that detect magic will tell you the presence of aura of invisibility (and if their willing to sit still the location). So arcane sight should tell you the same information as soon as you see it within 120 feet.
As far as I can determine, all you will be able to find out is the location of the aura (and presumably the size of what its concealing, say a small, medium, or large creature) but not if its a statue or creature thats under invisibility (unless its carrying gear or under the effect of spells).
Assuming that there is an invisible creature within your sight, what exactly could you determine about it? According to the spell you should be able to determine the auras of all of the active spells on the creature, as well as the magic items it is carrying.
Are you able to spend the standard action to focus on where the invisible creature is and tell if it is a spell caster and all the other possible information you can gleam?