The Fox/Disney release should earn around $51.352 million by tomorrow night, so at least it'll pass the respective opening weekends of The Wolverine ($53 million in 2013), X-Men ($54 million in 2000) and X-Men: First Class ($55 million in 2011). At this rate of descent, it'll lose screens by the barrel on Friday as Toy Story 4, Child's Play and Anna open in wide release, so even a $75 million domestic finish may be a pipe dream for the $200 million-budgeted Simon Kinberg flick.
For reference, the last "Dark Phoenix" movie, X-Men: The Last Stand, earned $77 million in its first two days of domestic release. Considering the budgetary differences, this will be a much bigger loss for all parties than Fantastic Four, which earned $56 million domestic and $167 million worldwide from a $120 million budget. Even presuming a 30/70 split, a $75 million finish for Dark Phoenix would mean just $250 million worldwide, or well under the $299 million global cume of the first X-Men back in 2000.