No offence, but … He took office in January, how could he be "largely" responsible for a development that started three years ago?
Obviously, the tariffs will have had some impact. But I'd reckon the Chinese brought this decline in foreign investment upon themselves, for the most part. They've strongarmed a sizable host of foreign companies out of previously amicable joint ventures, and continue to steal trade secrets like it's about to go out of style.
Investors want stability and legal certainty. Xi has erroded both.