It is my understanding that licensing SQL server 2014 with software assurance allows only one passive server per licensed server, having a failover server in the production environment plus failover servers in the DR environment would require additional licenses.

References:

SQL Server 2014 Licensing Changes by Jeremiah Peschka http://www.brentozar.com/archive/2014/04/sql-server-2014-licensing-changes/

SQL Server 2014 Licensing Datasheet http://www.microsoft.com/en-us/server-cloud/products/sql-server/Buy.aspx#fbid=2zKOgZheVEb