Hi is it possible to visit Jiuzhaigou in this coming Jan around 15-20 Jan. How's the weather?

Well, you can certainly go there for a visit. But it will be a little cold, with the average temperature of about 5C or a little higher in the daytime. At nights, you may feel colder, sometimes, it will be nearly 0C.
Therefore, you should take some warm clothing when traveling at that time.