Maybe in the US or Canada or other western countries. This isn't how it works in Japan. To their eyes, a foreign-born person will never be Japanese, let alone one who has moved to Japan when he was a full adult. I don't even think Yasuke would have ever viewed himself as Japanese. I know people who have emigrated to Japan and have been there for two decades and still don't consider themselves Japanese. Hell, you can even take it a step further. There are Japanese-born East Asians (Koreans, Vietnamese, Chinese, etc) who have been in Japan for generations and Japanese is their mother tongue and they still do not consider themselves Japanese, nor do the locals view them as such.
Being Japanese isn't just living on Japanese soil for a number of years. This isn't the United States where it started as a melting pot of different races and ethnic groups and where everyone, regardless of religion, ethnicity, or race, can become American.
So no, Yasuke was not Japanese by any definition of the word. Nobody calls William Adams Japanese because he wasn't.