I wonder how many of the STH purchase them solely for the purpose of reselling and profiting. Outside of the Edmonton game that had 1800 tickets available and the two nearest games, the rest had over 2000 tickets for sale, many above 2500 and at least one had over 2800. Not sure if greater than 10% is common but it was also the number of tickets available for all of the Detroit Lions games. It's far easier to throw tickets on StubHub or similar sites than having to stand outside the stadium peddling tickets. You could live on a Caribbean island, purchase season tickets for a variety of teams and try to profit. It's hard to imagine all of them profit but someone other than StubHub must be making money or the number of tickets posted would much lower. Long story short the tickets sold usually exceeds attendance, sometimes by a wide margin. Some of the more lowly teams like Florida and Carolina may prefer to announce the attendance as tickets sold than butts in seats however other markets may elect to announce the butts in seats as a way to let fans know they could have gone to the game and to encourage them to buy tickets instead of assuming games are sold out.
On the TV side of things it's not a big surprise that the ratings would go up. I'm not sure what they were pre-tank or when the team last made a playoff run but with Eichel and the other off-season additions most Sabre fans are ready to embrace the team.