No, I'm afraid you can't. :/
"What is this?" would translate to "Τι είναι αυτό/αυτός/αυτή;" Iin Greek. To translate the word πώς correctly, one would have to either use how, or what... like?
Πώς είναι αυτός; - What is he like/How is he?
I hope this is clear enough. ^.^