Doubt it, Iruka is too weak to be related to Hashi. Also, he has some other last name, I can't remember it right now though...
Iruka's family wasn't mentioned having to do anything with the Senju so I doubt they're related in any sense.
Iruka is Hashirama's grandfather. Don't ask me how this works.
I just found something that is interesting and opens a lot of possibilities... That or it is just an error in the series. Look below
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This guy name is TOBIO! Below
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and this guy name here now is TOBI! Below
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O....O! both characters have ''tobi'' in their names!!!
Is this conspiracy?! Those two may be related for having the SAME names just take out the ''O'' in tobio!
Iruka never mentioned being related to either Hashirama or Tsunade, so I've gotta say no.