At the current rate, taking into account the increase in sales near the end, 350,000 appears realistic. Even 400,000 is possible, though, at this point, seems a stretch.
If only 400,000 sell, the odds improve to the following (overall payback % improves to ~64% verses ~51%):
Top Prize 4 $1,000,000 1 in 100,000 (from 125,000)
Second Prize 4 $100,000 1 in 100,000 (from 125,000)
Third Prize 100 $1,000 1 in 4,000 (from 5,000)
Fourth Prize 5,892 $100 1 in 67.89 (from 84.86)
Totals 6,000 $5,089,200 1 in 66.67 (from 83.33)
If only 300,000 sell, which seems overly pessimistic, odds improve to (overall payback % improves to ~85% verses ~51%):
Top Prize 4 $1,000,000 1 in 75,000 (from 125,000)
Second Prize 4 $100,000 1 in 75,000 (from 125,000)
Third Prize 100 $1,000 1 in 3,000 (from 5,000)
Fourth Prize 5,892 $100 1 in 50.92 (from 84.86)
Totals 6,000 $5,089,200 1 in 50 (from 83.33)
So while the odds could be much better than advertised due to low ticket sales, winning something isn't a slamdunk. 1 in 75,000 is still slim. Heck, even winning the 4th prize isn't all that easy. 1 in 50, while better than 1 in ~83 isn't that easy to hit. Even if one spends $200 on 10 tickets, odds are 5 to 1 of winning zilch. In contrast, one could spend that same $200 on 10 $20 instant tickets and very likely get at least two winners to win $40+ back, and possibly hit for much more.
Another way to decide whether to go heavy on the raffle, is to view it this way. At 400,000 tickets sold, the overall payback percentage of ~64% is still somewhat worse than $20 instant games, which often have 70-75% payback, available right now, everyday. However, if one has reasonable confidence in ticket sales being far below 400,000, then it's possible the raffle will have a payback percentage, possibly upwards of 85%, better than anything else PA offers. However, to reiterate, at well over 400,000+ tickets sold, $20 instants have better overall payback. Something to keep in mind, if going all in on the raffle.
I currently have 1 ticket, and may buy some more, but not going on all in. Pick 5 is another avenue of winning $1 million with better odds and about the same payback percentage as the raffle 50% verses ~51%. $20 instants have better overall payback, and odds are far better of winning something than the raffle. 1 out of every ~3 $20 instants is a winner verses 1 in 50 for the raffle, at best, assuming only 300,000 tickets sell.
With all that said, I like the raffle concept, and hope the PA Lottery continues it. But it definitely needs some rework. In my view, run it monthly with 100,000 or so tickets offered each time. And/or offer a high-stakes raffle, such as 50,000 tickets at $50 or even $100 each. I'd buy one, and so would many others. Texas has long offered $50 instants, and they sell. There's a small, but solid market for high-wager players. PA should tap into that instead of marketing the raffle to the average lottery player who is hesitant to spend more than a few dollars on a numbers ticket.