loulutch Yes, you can use your ticket in First Class. A problem on this line is that the trains are short and have often not enough seats.
You can regularly check the timetables on bahn.de. When the train is cancelled, you can see « Trip is not possible ». For March 8 I see only « Notifications are available ». It means that it is now not clear it the train is canceled or not.
The strike should end at 1 pm on March 8, but it doesn’t mean that all trains will run after this time. It needs time to reorganize the network.
You can also download the app « DB Navigator » on your mobile phone, select the trains between Munich and Zurich and save them. You will get a notification if any change is planned. You can make seat reservations with this app.