Does getting into the force-emergent tree give u force rating +1?

I don`t think so, it sets it to 1 if you don`t have a Force Rating to begin with. If you do have FR, you have to take talents to get +1

As with any of these specializations you only get +1 Force rating if you purchase the talent Force Rating. Force Sensitive Exile and Emergent only give you a base Force Rating of 1 when you purchase them (if you didn't already have it), same as the Force and Destiny Careers.

The text at the top of the tree is precise: "Gain Force Rating 1." Not, "Gain +1 Force Rating."

If you need something more explicit, page 292 of AoR CRB tells us that a PC without a Force Rating receives FR 1 when purchasing the specialization. It then goes on to say, "However, if the character already has a Force rating of 1 or higher, it does not improve when he purchases the Force-Sensitive Emergent specialization."