The draft order is here: https://cdn0.vox-cdn.com/uploads/chorus_asset/file/7872567/P...
It doesn't mention the E-3 specifically, but the E-3 could come under review under the broader non-immigrant visa review provisions such as section 4d)i)A). The J-1 is specifically mentioned, which would affect Australian students on working holidays. Also, this order, if signed, would stop the international entrepreneur parole rule which would close another entry pathway.