According to Arum, minimum of 650k, he thinks it will do over 750k, and maybe it will reach 900k. That means it will never reach 900k, it probably wont do over 750k but it probably wont go lower than 650k. I think we are looking at 700k roughly. He did say JMM-Pac 2 was 4-500k, turned out to be on the lower end of that at 425k but still within the range he mentioned. We will know in a few days.
He doesn't want to show his hand. Once Mayweather/Mosley outsells this fight, PBF will absolutely refuse a 50/50 split.
Arum basically said it won't go below 650k. So it's probably 600k. Arum and his inflation of numbers.