The theatre is at letter T. This is now the block bounded by 4 sk, 5 sk, Bagyolu sk and Cetin Emec Cd on the Google map here.
This is in modern day Antakya is the site of a "park". We use the term loosely because we havent seen such a rugged urban park before. The main consolation is that this hasn't been built over and the town has clearly kept it for "future consideration". Our colleague, Jorgen Christensen-Ernst, ventured forth and took the following pictures recently.
Here is a view of the park from its lower western corner. The site is large enough to have encompassed a substantial theatre, with the implication that any excavation taking in the park and the surrounding streets (which are wider than need be) could reveal the complete structure.
This is a view of the park from above. One should imagine that one is standing upon the upper tiers of the cavea of the theatre here and that 1500 years of detritus moving downhill has largely filled in the slope of the structure. If the depth of the fill is anything like that in the old town (11 metres) then the lower levels of the theatre (the scenae and orchestra) could be in recognizable and quantifiable condition if the overburden is removed. This would involve losing the park and its stony wastes and dry pond.
This is a view from below showing the steepness above the theatre site (on the right of the street). If one can believe the story of the Persians surprising the locals at play in the theatre then it would have been from these upper slopes that they rained down their arrows on the crowd.
Poccardi says the theatre would have had a diameter of 120m, thus it almost certianly would have seated more than 10,000 people.