Unfortunately, there is not count for Azure table storage. You should consider using the Query Projection Feature
In addition, the projection feature will be useful in writing code that would count the number of entities in a certain table in a more efficient manner. We are working on providing Count() in the future, but until that is available Projection is useful since it will allow the transfer of a single property back to the client instead of the full row which makes the counting job more efficient. The code that highlights this usage is demonstrated in a later section.
Source: https://blogs.msdn.microsoft.com/windowsazurestorage/2011/09/15/windows-azure-tables-introducing-upsert-and-query-projection/
I'd also recommend checking this thread