New firmware updates for the two handsets have been certified by the PTCRB today. The build number in both cases (9.2.A.0.276) represents a significant jump from the previously certified software build (9.1.A.1.145), this leading XperiaBlog to believe that we’re looking at Android 4.3 here.
The support pages of Xperia T and Xperia V are showing that Android 4.3 is scheduled to arrive this month (the Xperia TX, which is closely related to the Xperia T, being in the same situation). However, there's only one more day left in December, so the updates will likely start rolling out in 2014.
As for Android 4.4 KitKat, Sony is currently investigating the possibility of bringing it to the Xperia V, Xperia T and TX. Since the smartphones are not older than 18 months, we're thinking that they should get KitKat eventually.
sources: PTCRB (1), (2), XperiaBlog, Sony (1), (2)