Kuroha’s first series were published in Gangan Online, the same web magazine as Nozaki-kun, so that’s probably the basis of their connection.
As for whether Kuroha may have been an inspiration, I’m not sure. I know Nozaki-kun and Kuroha’s Kitakubu/Magical Lollipop started the same month (although the Kitakubu oneshot was released some time earlier). I’ve not actually read Nozaki-kun, so I don’t know how early this famed tanuki mangaka was introduced. If it’s very early I feel like it’d be unlikely, since Kuroha wouldn’t have solidified it as his brand just yet. Later down the line, maybe?
As for why Kuroha himself includes the seals, in one of his twitter comics he says “filling in empty space with an animal” is something he “learned” from a manga called Kiyomura-kun to Suginokouji-kun. Which I’ve also not read, but which, from quick image searching, does appear to use mascot animals in a similar capacity. This KiyoSugi was also a Square Enix-published manga, so I imagine it also could have been a potential influence on Nozaki-kun (again, not having read either).