AutoCAD 2017 has been released so probably soon the question will come up whether ARCHICAD can read AutoCAD 2017 format DWG/DXF files.
This blog post answers that question as it states that the DWG/DXF file format did not change in AutoCAD 2017 so it has remained the same since AutoCAD 2013. This means that ARCHICAD will be able to read AutoCAD 2017 DWG/DXF files just as it can read previous version DWG/DXFs.
Autocad 2018 came out in April 2017. ARCHICAD 21 came out in June 2017 so it could not incorporate v2018 DWG/DXF support (at that time of the year the new ARCHICAD version is already in beta phase, just as this year). Hopefully, ARCHICAD 22 will have v2018 DWG/DXF support.
Till then, you can download the free Autodesk DWG Trueview application and convert that v2018 file to v2013 file, which AC21 will be able to read. Please not that it can convert DWG files, but not DXF and DWF files: