The only way I have interfaced Gerber files with Pro-E is to DXF out of Pro, import the DXF into a host program and output the Gerber files from there. In our case the host program is a fabric cutting software called CutWorks.
You can write plot files in Calcomp, Gerber, HPGL2, and Versatec format if you have the Pro/PLOT module. Pro/PLOT is part of the Foundation II license.
