It's been pointed out by some critics that the Pixar house style is in some way informed by the work of Hayao Miyazaki. IMO this is easy to overstate. It's true that Pixar honcho John Lasseter has expressed admiration for Miyazaki, and has produced several english dubs of Miyazaki's features. But I think Miyazaki's influence is more general than specific in nature. Like Akira Kurosawa before him, Miyazaki's successful brand of film making has a knack for flattering Western sensibilities while appearing foreign and exotic. And in Hollywood where animation is dominated by big studio concerns, the individual stamp found in every Studio Ghibli feature is an alternative model for Western animators to emulate. This is what Pixar has arguably more or less achieved with their body of work. Lasseter has become identified with the Pixar style as much as Miyazaki has with the Ghibli style. But Lasseter and Miyazaki possess very different styles as auteurs.
The most that could be said about finding something in common between Up and Miyazaki's oeuvre is that Up shares a similar romantic fascination with escaping the mundane by taking flight, both figuratively and literally. Even here the film's approach is relatively constrained. For a movie about a flying house the flying sequences are all too brief and claustrophobic, especially when placed next to works like Porco Rosso. Even the targeted destination is itself pretty mundane - a postcard view from a generic South American jungle. The closest Miyazaki film I can think of that Up has in common is Laputa: Castle in the Sky, in that it is an adventure story where the heroes prevent a two dimensional villain from raping and pillaging nature (Unusual because Miyazaki's most memorable villains tend to have redeeming qualities). But the character archetypes and plot of Up owe more to classic Hollywood comedies to be directly compared to Miyazaki's environmental fable. Even the ending of Up has to make concessions to Hollywood-style mawkish sentimentality.What most Western studios cannot or will not replicate is Miyazaki's attitude towards nature. In Up nature is something pristine and innocent for people to admire, or a resource to exploit and destroy. It's a typically Western viewpoint that can lead to a zero-sum game. But in Miyazaki's most memorable stories, probably informed by Shintoism, nature is to be revered. Nature is a dangerous entity that can fight back when pushed to far, and even when battered and buried by the detritus of human civilization (As in Spirited Away) it still possesses great potency. Nature can hide the mighty Ohmu, or ancient gods and spirits. But in Up, nature hides a multi-colored version of the Road Runner.