Back in v1.3c I added support for most of the common DXF entities, which included splines and beziers (curves and other shapes were already supported, the only exception is text).
I don't really use beziers myself but following a post over on the BCL thread I did some testing.
Here's a quick example using TurboCAD, the bezier imports perfectly.
I've noticed that some programs don't do a great job of exporting them accurately in which case they won't be correct in T2Laser but I can't fix what another program does incorrectly. It will depend on the CAD software, in particular I've noticed some odd errors with Inkscape but not always. So I still recommend converting to polylines or curves when exporting.