He's saying that Soros directly supports policy that forces countries to accept migrants. Historically, alongside massive inflows of migrants there have been tremendous rises in violent crime and sexual assault in Northern European countries. As a prime example, take a look at related data for Sweden.
Sweden changed its statistical method quite a bit (eg counting each 'act' within a rape separately), that, together with much more awareness of sexual violence and a campaign and social changes encouraging victims and witnesses to report things had a huge effect on the statistics. Wikipedia has a decent-ish summary of the changes. Sweden doesn't collect data on perpetrator background or similar, so literally all of the articles in (primarily Anglophone) right wing media claiming statistics on that are simply made up. That being said, I'd not be surprised if numbers went up with an increase young single men, but the data simply does not exist to prove either way. The natural tendency is to guess the correct interpretation and read it onto the data, but it simply is not there.
The paper you tried to link to didn't draw any connection between immigration and rape. The increased number of reported rapes in Sweden in the late nineties could be explained in a number of ways. One is that reporting increased thanks to increased awareness, another is legislative change, a third is revision of statistical routines. The two latter are mentioned in the paper.
Another thing that complicates a comparison:
"The Swedish data tend to lie at a higher level than that of the other countries (von Hofer, 2000). This is due to several factors: 1) in Sweden, a criminal offence is registered at the point that it is reported; 2) reported acts that later prove to be non-offences are not removed from the statistics; and, 3)
all offences listed on the same police report or committed on the same occasion (or in a series) appear as separate offences in Swedish statistics. Thus, the number of offences counted in Sweden is more comprehensive than in the other Nordic countries." (p. 7)
www.nsfk.org/Portals/0/nordicstats_1950-2000.pdf