No, RAW files cannot be directly opened in Topaz Labs. If working with a raw image, you'll need to covert the raw file with an editor like Adobe Camera Raw first. You can then bring the raw file into Photoshop via ACR and work with the image that way in Topaz Labs.
Another option is in Lightroom, you can open the file as a smart object in Photoshop and then bring the image into Topaz Labs.
See here for additional information on converting RAW files to JPEG.