Not sure how they know but apparently many of the viewers are said to be repeat viewers:
http://www.hollywoodreporter.com/news/j ... ens-921406With only a couple weeks left in its first run the film seems certain to break 50m, but 60m seems out of range on the big guys 62nd anniversary. Still China's ShinGoji run opens in a couple days. Not really sure how past films have done internationally but if it generates enough buzz in the Pacific perhaps funi will consider extending its run here.
As for the Olympics, I assumed Abe did that because the pipe entrance was more discreet than having a giant monster tear through Rio. Plus there's already Mario and Sonic at the Olympics games so it was somewhat witty. Methinks we'll be seeing Goji in Tokyo, since they don't seem scared to shy away from their pop culture icons and Godzillas popularity is likely to be at an all time high with sequels to this and Godzilla 2 in the works.