Orochi 3 is Japanese voices only for the time being.
I don't know if they'll release an English voice addon later or not. Honestly I don't think it's needed. Most DW/SW fans complain about the bad/cheesy English voices anyways, not to mention the mangled pronunciation of the Chinese names DW7 finally got it right.
My only complaint with the Japanese voiceovers is that the Chinese names have totally different pronunciations that are based on the Japanese language's use of Chinese characters. For those of us who know a little Japanese, this makes it nearly impossible to follow the Japanese dialog.