Estimating the materials needed for steel stud framing is much the same as for wood wall framing. It can be done the same way that wood walls are build.
Alternately, lay out and install the upper and bottom tracks but leave a gap in the inside corner and partition walls for the drywall to run through. Leave the stud that butts into the other wall loose and run the drywall through first. Once the first wall is boarded attach these studs in place. This will save you some studs and makes for strong wall joints.
The estimation of steel studs needed is based on running the drywall through. If you are not doing that add one stud for each partition and one for each corner in your project.