This Cracked article says that the Oracle at Delphi got her “powers of prognostication” from being put into a hallucinatory state brought on by gasses being released from an underground spring.
A quick Google Image search reveals that the ruins of the Oracle are still there, and are presumably a stop on the tour. But are the hallucinogenic vapors still emanating from the springs? Can visitors inhale them and [del]get high[/del] have prophetic visions?
This article speculates about the gas. I don’t think they actually found it. Note that the article say “were likely” and “are likely”. They are speculating.
It is odd that they can’t excavate and actually find the gasses/vapors.
A quick googling leads me to believe there’s quite the slapfight going on about what exactly got the pythia high. One team in 2001 found traces of ethylene in the stone walls. Another group in 2006 thinks it’s oxygen deprivation coupled with benzene. At any rate, it doesn’t sound like there’s really agreement on the actual mechanism and given that, seems unlikely someone now could replicate the Delphi experience.
We don’t know for sure how the oracles did their thing - not at Delphi, and not elsewhere. Psychoactive substances is only one possibility among many.
And no, present-day visitors don’t get high there. I mean, they might, but only if they bring their own goods. 
Doctor Who used this idea in Fires of Pompeii. This was during David Tennet’s run. The maidens were sniffing the fumes and seeing visions. Just like the Oracle of Delphi except, they were turning to stone too. 
I read about this, I think, Scientific American, once. As far as I can make out, the whole theory was ever anything more than a piece of baseless speculation in the first place. On the one hand, although it is possible that there were once high concentrations of ethylene (or whatever - it doesn’t really matter) there, there is not, and is never likely to be, any compelling evidence of it, and ethylene (or any other gas that plausibly might have been there) is not all that psychoactive anyway. On the other hand, you do not need to appeal to any such thing in order to more plausibly explain the stories about the oracle: maybe they were just making stuff up to fleece the rubes; maybe they were getting themselves into a trance by chanting, or some form of hypnosis; maybe they were using plant-based hallucinogens (likely to be a lot stronger, and safer, than any gas wafting up through cracks in the ground.
So no, not only are the “vapours” not there now, it is more than likely that they never were.
The real problem her is physical scientists who think they should have all the answers, but do not understand how societies, psychology, and historical standards of evidence, work.
I’ve been to Delphi, and I certainly didn’t notice any “buzz” or anything out of the ordinary. Seems to me if there were weird gasses coming out of those ruins, it would be a big deal and there would be signs posted warning tourists about it. There aren’t any signs, and I don’t recall it being mentioned at all.
So, we’re ruling out the God Apollo, then?
I just thought they were faking it.
There were a couple of familiar faces in that one, Peter Capaldi and if you squint real hard you’ll see one of the Virgins was Karen Gillan.
Tsipouro.
Actually, I’ve been there too and didn’t see any sign of geothermal vents, hot springs, gases eminating from the earth, or any of that.
From what I read of the prophecies or whatever you’d call them, it sounds to me more like some appropriately “delphic” clever thinking and not at all anything like the product of intoxication of any sort. Scented smoke in the sanctuary of the Pythia would suitably impress visitors/supplicants and enhance its mystic quality. For sure, the oracle wasn’t short on money.
We do know from other places in the Hellenic world that the priests weren’t entirely above a bit of stagecraft and trickery. IIRC, Heron of Alexandria made more than a few clever devices for this purpose.