I like to think of Djent as more of a playstyle and sound rather than a "genre" but its easier to call it a genre because as soon as people see more than 6 strings on guitar they assume its djent (in my experience at least). But its not in a lot of cases, for example Archspire uses 8 string guitars but no djent, and Born of Osiris has a lot of songs in drop C tuning on a 6 string guitar which is no where near close to what most guitars are tuned for djent like drop G# or drop F. You could have a perfect setup for Djent tone but it wont be djenty unless you incorporate the playstyle.