Having elders is biblical, there is plenty of mention of elders and how they were to help the congregation. It is not something that identifies the WTS as God's people though, as a heirachy of elders is common in religious groups.
What is not biblical is many of the functions of Watchtower elders;
- report cards on field service
- judicial committees for disfellowshipping - the congregation not a closed group of leaders used to make the
- the way elders are appointed - ie. recommendations approved through Bethel
- A Governing Body making unquestionable decrees - Acts 15:2 says it was a large body of elders that were involved in the circumcision decision - "they arranged for Paul and Barnabas and some others of them to go up to the apostles and older men in Jerusalem regarding this dispute."