SketchUp does not support import of JT file natively, which means jt to skp conversion is a bit problematic. But you can download and use the JT importer for SketchUp from Simlab and add this functionality to the software. The only alternative to this would be to export the .jt file to some exchange format that is accepted in SketchUp by default, for example FBX or OBJ.
Updated: August 28, 2023