Hi Ketan,
It's a two step process
Step 1: Enable success and reject from update data activity(this will work for CRM export activity as well)
Use the following screen for the reference.

Step2: Use vars.recCount or vars.insertCount & vars.updateCount to get the count of records, you can use this variable to do what ever you want to use it for.
Example logInfo("successfully inserterd or updated records: "+vars.recCount);

Hope this helps!
Amit