One minute per page is an approximation across the whole script. So any given single page might be more or less than one minute, but across the whole script it typically works out to that.
That being said it really comes down to editing, blocking, delivery, etc. So a 100 page script could net you anything from 90-120 minutes of screentime.
I expect this film to be around the 100-120 timeline. Most of the Predator movies are 100 minutes and most movies these days seem to be around that length.
