Are there a topic on BT with job offers ?
Unfortunately there's none (afaik).
If no, are there any sites, where I would have capability to find job in cryptosphere?
Yes, you can try the following (I can't vouch for any of the following platforms [never tried them]):
Actually, there is. Check out this thread here,
https://bitcointalk.org/index.php?topic=2165225.0 and see if there's anything you might be interested in. There's tons of projects looking for ICO managers etc.
Things like
this might be interesting for you, although i'm not sure how legit the projects/job offers are that have been listed there, so take care.