They have oriental features, due to persecutory rapes while in China, but since Jewishness is determined matrilineally, that is irrelevant to the fact of their Jewishness. But after a couple of millennia of inbreeding amongst themselves, the Chinese Y chromosomes would be ubiquitous and queer any DNA tests. My guess.
Even if Chinese Y-chromosomes predominate, if the Bnei Menashe are descended from the tribe of Manasseh maybe some Israelite haplogroups would be found.