From Hakodate to Niseko

We will be departing from Hakodate to Niseko self drive end Nov, pl advise if it is safe.

It's too early in the season to really know what the road conditions are going to be like this far out. But, I have taken the bus from Chitose to Niseko in late December. Once we were out of the city, the roads were covered in snow with new snow falling, but the bus just kept rolling. Just make sure that the vehicle you are driving has snow tires and I think you should be fine.

Any gas stations along this path from Hakodate to Niseko village, and where are they located?
& pit stops
And my next stop is Otaru, again anyone can help to advice how is the road condition? Hilly? Any gas station and pit stops.

Been a while since I have driven this route, but I never even worried about gas stations. There are plenty along the coast and if you follow the Hakodate Line through Kuromatsunai and Rankoshi. Some of the smaller mountain roads don't have stations or much else, but the distances aren't far enough to burn a full tank of gas. Just take a look at Google Maps and some will pop up.

https://www.google.com/maps/search/gas+stations/@42.7314045,140.413189...

Your rental car will most likely come with a navigation device. You can set it so it shows on the screen upcoming gas stations.

According to weather forecast Niseko start snowing next week also Hilton village. I�fm driving a 4 WD car with snow tires , anyone could advise on the safety (road condition) and special things that I have to take note.

If you are going to have 4wd with snow tires, just use common sense. Don't speed. Leave plenty of room between the car in front of you. Don't slam on the brakes. Shift down, if you're going downhill.