At least according to Stratford*, which is the classic caving guide to the area. However, the recently extended Ogof Draenen (1994: if "extended" can adequately cover 66km of new passage: Info; Info) was previously only known as a short passage ending in a blockage, from behind which came a strong wind. On the basis of these details, it is hard to assess whether this cave would be appropriate. However, as it is in more or less the same position and geology as the Llangattock caves, only across a dividing valley, it would seem to back up the general likelihood of the cave being in this area.
Two additionally interesting caves are listed by Oldham*. The first he quotes from the "Cambrian Travellers Guide" of 1813:
The other [cave is] called the windhole... its depth from the entrance measures 27 yards [24.6m]. There are two or three fissures through the roof of the cavern to the land above, and a considerable distance from the edge of the cliff; over which a hat is placed it will be blomn[sic] back into the air with considerable violence, but this only happens when the wind blows fresh from the south-east.
Oldham notes that this is shown on 'the sixth inch series' maps as Pwll-y-Gwynt. Unfortunately its location, east of Ogmore-by-sea (on the cliffs next to The Flats) is outside Gwent.
The second cave he mentions is quite bizarre. He claims that every 10 seconds, for 5 seconds, it breathes out a warm, steam-like, breath ("the dragon's breath") which is off-putting for anyone who'd like to enter. He suggests it might be from an underground fire, or gas from decomposing organic material.
This matches with a suggestion by Edens* that the translation of Gwynt should be "flatulent" and/or "blast", and that the wonder is actually a methane outlet from a coalfield, hence its impenetrability. Pliny the Elder lists a number of deadly cave winds in his Naturalis Historia1, but these are largely in more active geological areas where volcanic gases are likely. That the Historia should be describing methane seems somewhat unlikely - the description would surely have noted the explosive nature of any such outlet more explicitly, and the Latin seems to match the standard interpretation. Either way, Oldham's cave is unlikely to be the wonder, as it is in Tythegston Quarry and, therefore, a good distance from Gwent. It should be noted that the cave is probably not marked on the 1885 map (there is a slight indent that might be the start of the quarry), and that since Oldham wrote the quarry may have been filled with waste*.
Additional caves outside the area with suggestive names include Gut Hole, on the Gower, and Hot Air Mine in the Swansea valley, both of which can be found in Stratford*.