Although it certainly matches the high-rhetoric in which Assange is so fond of writing, I've come to the conclusion that this line was an invention of the screenwriter, not least because Assange has spoken extensively about how one can change the world (in this case by understanding history and rejecting the conclusions) without ever mentioning "committment" and/or "sacrifice"
We live in the world that we perceive. Our limits are the limits of
our perceptions. This generation knows more than any previous
generation. Its actions will eclipse those of previous generations. We
change the world by observing its behavior, thinking about our
observations and acting on our thoughts. To observe we must open our
eyes. To think we must open our minds. To act, we must open our
hearts. Our eyes have never been so wide. Our minds never so trained.
And the courage in our hearts spreads like a contagion.
There's also a brief mention in Assange's autobiography about a blog post on his old site about how "true committment" is demonstrated
"when they break down your door with their jackboots".
Nothing to do with changing the world.
As far as I can tell, the quote is, at best, an amalgam of things he's said elsewhere and at worst a total fiction.