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You used to be able to tell by sending an imessage and having it go green and sending as sms, that would be a tell. (if you did this several times over an x amount of time) However they have changed that in ios9, so if you send an imessage and they have you blocked, it'll show up as delivered.
You can test this theory by sending yourself a text and then blocking your number. Every time you send a text it'll show up as delivered right away.
So to get to the answer, no. I would try later to send a text. You could also call and if it rings once then goes to voicemail that could indicate it's blocked.
Checking in to see if you still need help with this issue, if so please reply at your convenience