The Noble Eightfold Path is exclusive to Buddhism, whether discovered by Gautama Buddha or Buddhas before him.
As stated in Dhammapada 254 - 255, noble contemplatives cannot be found outside the Buddha's teachings. The term "noble" or "ariya" here is a technical term in Buddhism, and doesn't refer to its ordinary meaning.
The simplest hint is that you cannot find the Right View of the Noble Eightfold Path outside Buddhism.
Of course, you can find eightfold paths anywhere.
For e.g. in the famous Hindu text Yoga Sutras of Patanjali, he taught the Ashtanga Yoga or Eight Limbs of Yoga.
And guess what image I found on the Ashtanga Yoga wikipedia page:
That's certainly an eightfold path, just not the Buddhist noble one.
Also please see this answer.
Even within Buddhism, there is both the noble and non-noble versions of Right Action, Right Speech, Right Livelihood and Right Thought (according to MN 117). The noble version applies to Buddhist monks while the non-noble version applies to Buddhist lay followers.
I speculate that the non-noble version of Right Action, Right Speech, Right Livelihood and Right Thought (according to MN 117) may also apply to followers of other religions, but only if they follow the definition strictly.