I have heard varying opinions. The only thing keeping me from saying yes is that he unified German to further his conservative government's cause, not really because he thought all German speakers should be united.
This is an extreme example, but for example Hitler starts off Mein Kampf by mentioning that Austria and Germany ought to be unified, even if it had negative economic repercussions. Bismarck wouldn't have done that, he thought of things more logically and rationally. What do you guys think?
The distinction Hitler was making (and greatly simplifying) was between two positions called Kleindeutschland (lesser Germany) and Großdeutschland (greater Germany) with Hitler obviously pushing the latter. In general, the Kleindeutsch position stressed that Germany should unify as a political entity consisting of the core German states. These central European states were allegedly ethnically and linguistically homogenous (on the ground, the various German states were far more diverse, but nationalist activists often overlooked this). Incorporating Austria would have meant adulterating this new German polity because in addition to Austrian Germans, the Austrian Empire contained many Slavs and other non-Germans. One of the big sticking points of the Paulskirche debates about German unification in 1848 was whether the Austria empire could be incorporated into a new German union given the size of its non-German population. The only real practical solution to this impasse would have been a real or de facto dissolution of the Austrian empire, which the Hapsburg emperor would not permit. Therefore Großdeutschland or pan-German activists in the nineteenth century often saw the old imperial house as a barrier to their aspirations to unite the whole German cultural sphere.
Now as to where Bismarck fits within Großdeutschland/Kleindeutschland nationalist position, the answer is really neither. Bismarck was very much a Prussian nationalist and sought to strengthen Prussia. The Kleindeutschland position allowed for Prussian leadership of the united Germany. But as a practitioner of Realpolitik, Bismarck kept his options open and at various times in his career never committed himself to a single political strategy. For example, during the Crimean War, he pushed for a unification of the northern (i.e. Protestant) German states with Prussia that excluded the Catholic south, but he reversed course in the 1860s. By tacking to a Kleindeutschland position in the 1860s-70s, Bismarck became the champion of a type of German nationalism, even though the imperial structure he created privileged Prussia and the Hohenzollerns. For Bismarck, Prussian nationalism was the nationalism of Imperial Germany; he saw the two as complimentary, not as fundamentally oppositional.
Sources
Pflanze, Otto. Bismarck and the Development of Germany 1. Princeton, NJ: Princeton Univ. Press, 1971.
Steinberg, Jonathan. Bismarck: A Life. New York: Oxford University Press, 2011.