What are the origins of Naruto's stomach's double tetragram seal? The center pattern looks like an Aztec symbol for rebirth but I'm wondering: How did Kishimoto come up with this exactly?
I can't seem to find any official information as to where the Eight Trigrams Sealing Style originated or was based on. 

However, here's a theory. 

As you may know, Naruto has many influences from Buddhism and Hinduism: the Multiple Lotus Nonself Connected Cannons, The Six Paths of Pain, Formation of Ten Thousand Snakes and the Chakra, to name a few, were based on Buddhist and Hinduist beliefs.  

With that, I say that it's possible it might be inspired from the Dharmachakra or the wheel of Dhamma. A comparison of the seals are shown below: 

According to Wikipedia, it is connected to the Four Noble Truths and the Noble Eightfold Path, both of which are teachings to help a person escape the painful cycle of rebirth, if I understand correctly.