Mavis is NOT giving them orders. The things she says are in the future tense (Juvia will do this
, Erza will do that
, Gajeel will beat this enemy
) or the team members say that their fights were predicted by her (Erza and Gray both said something along the lines of "this is just as First said") and speak of those events in the past tense. Also, the entire time she's speaking, she isn't even talking to the individuals in the team. Not once did she say "Laxus, you will go here" or "Gajeel, you will beat them".
The only thing in this entire chapter was when she yelled out "move". That is akin to a football fan screaming at their tv for a guy to be tackled.