First of all, we need to clarify what you're asking. Are you referring to the Great East-West Schism of 1053 in which the Pope and the Patriarch of Constantinople mutually excommunicated one another? Or are you referring to the Great Western Schism 1378-1418 which resulted from the Avignonese Papacy and the election of two, and later even three popes? In either one of these scenarios, asking about Austria is problematic. Until the later fifteenth century it's neither an important European entity nor a bi-confessional state. Likewise, there was no "Italy" until the risorgimento (Italian unification) in the nineteenth century. Until then, the Italian Peninsula was occupied by a dozen competing principalities. The Kingdom of Sicily and the Kingdom of Naples functioned as a bi-confessional states, with both Western (Latin) and Eastern (Greek) Christian populations. However, due to the proximity to Papal Rome and the fact that the ruling families identified as Latin Christian, Catholicism remained politically dominant. Poland accepted Latin (Western) Christianity starting in 966 and it remained the state confession thereafter. In 1349 Kazimierz III (The Great) acquired eastern Ruthenian lands that made Poland a bi-confessional state with a sizable Orthodox (Eastern) Christian population. This Eastern Christian population increased in size further after 1385, or the establishment of a personal union between the Kingdom of Poland and the Grand Duchy of Lithuania. For the next two centuries, the Polish-Lithuanian state was home to a large and powerful Orthodox Christian nobility. However, they were never a threat to the dominant Latin Christian (Catholic) creed, especially since the Crown remained Catholic. In the Middle Ages, as in the Reformation, the ruling authority tended to be a determining factor in confessional predominance.

Gerd Tellenbach, The Church in Western Europe from the Tenth to the Early Twelfth Century, Cambridge, UK: Cambridge University Press, 1993; Steven Ozment, The Age of Reform, 1250-1550: An Intellectual and Religious History of Late Medieval and Reformation Europe, New Haven: Yale University Press, 1981; Norman Davies, God's Playground: A History of Poland, Vol. 1: The Origins to 1795, New York: Columbia University Press, 2005; Kościół w Polsce. Tom I. Średniowiecze. Jerzy Kłoczowski, ed., Kraków: ZNAK, 1966.

Those areas that were within the canonical territory of the the Bishop of Rome became Roman Catholic when Rome separated from the rest of the Church during the Great Schism. The Italian peninsula was always within the sphere of Rome for obvious reasons, and the previously pagan regions of Poland and Austria were evangelized and Christianized by missionaries sponsored by Rome, and so came under Rome's purview as well. In general Rome's area of authority was by far the largest of the "big five" ancient sees (Rome, Constantinople, Alexandria, Antioch, Jerusalem), since it was the only one of them that was located in the Western half of the old Empire, so the whole West was Rome's responsibility.

Keep in mind that the Great Schism wasn't really a singular event... although the mutual anathemas of 1054 are usually cited as the "date of the Schism", the separation of the Eastern and Western halves of the Church was a very long and gradual process that had begun many centuries before. It was a (very-)slow-motion train wreck all around.

Large parts of Naples and ofc. Sicily was still under the control of the Byzantine empire by the time of schism and therefore remained orthodox. If you see a map of the world on the schism, you can see that it foremost have geographical reasons. http://upload.wikimedia.org/wikipedia/commons/6/67/Great_Schism_1054_with_former_borders.png The Byzantine (East Roman) empire also had most authority in the east, Rome (former seat for the Western Roman empire) had obviously most authority in the west.