The answer is "maybe" despite the rather definitive claims found here. For a more skeptical take, see here. For some feminist reaction, see here. The idea is that rape rates have gone down while widespread availability of internet porn has gone up. And the biggest drop in rape convictions has come with the group that is supposedly most likely to rely on internet porn: 15-19 year olds.
There are plenty of issues that one might bring up. Rape convictions might underreport rape behavior, for example. Or you might argue that this result makes no sense because "rape is about power." But these objections don't seem to be very strong when faced with actual data. It seems to really amount to the claim "The study must be wrong, so let's find some reason to hold on to that belief." Surely, convictions are a not terrible proxy for rape behavior (that is, rape convictions go up when there is more rape and go down when there is less rape). And surely a theoretical point about the nature of rape has to give way to empirical claims about what actually causes it or prevents it. At the end, I might point out where you might be skeptical of the claim of the study.
And while the idea that pornography prevents rape might seem a bit crazy, the idea that pornography causes rape, a central tenant of some feminists, seems to be quite unsupported. Usually, the pieces of evidence provided are anecdotal stories that indicate that some rapists also look at pornography. There are other studies that indicate that pornography sometimes temporarily affects people's attitudes towards women, but there isn't any evidence indicating that that change in attitude makes it more likely that they will engage in violent behavior towards women. There aren't any studies available that indicate that wider availability of porn in an area correlates with an increase in instances of rape. I am off the opinion that the current problematic instantiations of pornography in our society and the high rates of assault and sexual assault towards women are symptoms of the fundamental unfairness in the distribution of primary goods that face women.
But there are other reasons to be skeptical of concluding from the study that viewing internet porn itself prevents people from raping or becoming rapists. Rather, I think the widespread availability of internet access and computers and its attendant socializing changes in adolescents have, as a consequence, preventative effects themselves. So, actually viewing porn does nothing itself.
P.S. I would like to point out this post's analysis seems simply wrong. First, the fact that some porn stars do degrading sexual acts is no evidence that they are being raped. Subs like and consent to degrading acts because they enjoy them. Some agree because there is money in it. This is not to deny that rape happens in the porn industry, but rape happens in any industry that involves women, so I find it hard to see why this is an objection to porn qua porn. Second, to argue that sometimes built up sexual frustration could cause someone to rape does not mean that the women deserves to be raped; it doesn't even suggest that. Some people kill because they are very angry or upset or otherwise emotionally distraught. This doesn't mean they aren't responsible for their actions, and it does not mean that the victims somehow deserved it.