Popularity of girl = check previous event for that girl, they keep the max cutoff for girls pretty much capped at 70-72k in jp for 2nd tier (International doesn't get that high for 2nd tier)
As for how people around the globe affect the event, just check https://sites.google.com/site/llsifenev ... rent-event . You can look at the change in cutoff per hour, and it is pretty consistent across the board unlike jp. JP has a very set pattern as shown in the jp equivalent tracker http://llborder.web.fc2.com/
Using all of that, you can easily predict how much you need to get the tier you want. The question is more, do you have the time to dedicate to get the tier you want.
As for how people around the globe affect the event, just check https://sites.google.com/site/llsifenev ... rent-event . You can look at the change in cutoff per hour, and it is pretty consistent across the board unlike jp. JP has a very set pattern as shown in the jp equivalent tracker http://llborder.web.fc2.com/
Using all of that, you can easily predict how much you need to get the tier you want. The question is more, do you have the time to dedicate to get the tier you want.