Why did the Habsburg Empire survive the 1848 revolutions?
There were two major factors that helped the Habsburg Empire in Austria survive the 1848 revolutions. These were A) the fact that some of the opposition to the Empire was divided and B) the fact that the Empire was willing to use force to put down the rebellions.
As an example of the first factor, the Hungarians attempted a nationalist rebellion in which the tried to create a separate Hungarian state within the Empire. The Hungarians tried to take areas (including places like Croatia) that had nationalist ambitions of their own. The nationalists in these areas fought back, weakening the Hungarian rebellion and thus helping the Empire. As an example of the second factor, the Austrians, with help from Russia, sent a huge army to crush the Hungarians when they attempted a last-gasp rebellion in early 1849.
In these ways, the Habsburgs were able to survive the 1848 revolutions.