How does 1984 show that hatred has a more powerful effect upon people’s actions than love?
I disagree with the premise of the statement. I think it is clear that 1984 shows that FEAR has a more powerful effect on Winston's actions, ultimately, than love.
While it could be argued that Winston was made to fear out of hatered, I do not think that the text clearly shows that O'Brien, the personification of Big Brother, acted out of hatred, I think he was actually dispassionate and acted merely out of political corectness.
While Winston did confess to crimes that he committed and even some that he did not, and while he did implicate his love Julia, he did not give up loving her until he was confronted by his greatest fear.
When they encounter each other later on, they both confess to having betrayed the other. Julia confesses that:
"I betrayed you," she said baldly.
"I betrayed you," he said.
She gave him another quick look of dislike.
"Sometimes," she said, "they threaten you with something — something you can't stand up to, can't even think about. And then you say, 'Don't do it to me, do it to somebody else, do it to so-and-so.' And perhaps you might pretend, afterwards, that it was only a trick and that you just said it to make them stop and didn't really mean it. But that isn't true. At the time when it happens you do mean it. You think there's no other way of saving yourself and you're quite ready to save yourself that way. You want it to happen to the other person. You don't give a damn what they suffer. All you care about is yourself."
"All you care about is yourself," he echoed.
"And after that, you don't feel the same toward the other person any longer."
"No," he said, "you don't feel the same."
I am not sure if I am willing to go with hatred being more powerful than love in the book. I will say that the book shows fear being more powerful. In either case, I can go with love as being secondary in the book. I think that part of this comes from the fact that Orwell is dying as he is writing the book. Certainly, this aspect of knowing one’s reality and one’s fate that cannot be avoided and is inevitable is something that looms over the reading of the novel and Orwell’s writing of it. We can see this in how the love affair between Winston and Julia is shown. The initial hope and expectation of the reader is to hope that there might be some level of liberation and some level of freedom expressed in their union. Perhaps, we can view this as the act that will challenge Big Brother. Yet, Orwell recognizes that there is a narrative of history that features loss and abandonment. Justice does not always win out in this conception and that people do betray one another, so much so that the names of these people are too long to catalogue or placed in a list that is later to be mislaid. This reality is what the reader gets when both lovers renounce one another and repudiate one another. When Winston is tortured with his greatest fear of rats, we see in this moment that fear beats out love. When he is released back into society, he is a gutted shell of a man, fear having created a crater of emptiness where only bad gin is ingested. When both of them meet after having sold the other out, there is a sense of anxiousness present, not lost love or the begging of forgiveness. When we see Winston as having learned to “love Big Brother,” we see a love that has been carved out of fear and out of intimidation.