Yes, you can! There will probably be some pubs here and there which will show the action, but the best solution is probably to follow the instructions which you can find in this article on www.watchworldcup.net.
Unfortunately (or maybe luckily) rugby is not at all a popular sport in Vienna and in Austria, so there are very few who are actually interested in this sport. Football is a much more popular sport and with the Austrian national team progressing and getting better and better, this is the sport that will attract crowds in Austria, something that can not be said about rugby. So, if you find some live broadcast from the rugby world cup in a pub or sports bar in Austria and in Vienna, please write a comment to share information about its location so that other visitors to this page and article can get hold of that information. Until then we recommend watching it online and you can find the instructions on how to watch it online in the article linked to above.