I'm sorry, which part of that "Seals" it ?
It wasn't said by Gabe , it was just stated by Joystiq .
This very same thing can be found at Gamespot
"Dota 2 is scheduled for PC and Mac release this year."
And under the image
"Expect DOTA 2 to leave beta early next year."
Why these websites wanna make assumptions is their business but let's not CONFIRM, its true unless stated by an official.
It doesn't matter what people think, it doesn't matter how calculative you can be, all we know is the officials are aiming for release around the end of this year, that's all we can really take now.