(OP) A person could certainly survive the night with mild internal bleeding. It might even resolve itself without medical intervention over time. However, if it is mild I wouldn't expect bleeding alone to cause unconsciousness of any significant duration.

Regarding what 911 would advise, if the patient is breathing, they would likely say not to move them and to wait for EMTs. Just keep in mind that there needs to be a reason for someone to suspect internal bleeding, and whatever evidence points to that might change what the advice might be.