It would help if you told us why you want the server; what your goal is. Even without this knowledge, I will be able to answer your question.
Simply, no. The card doesn't advertise room for 6 GPUs. It advertises 6 slots that COULD be used for GPUs. Not only will it not support 6 GPUs, it will not support either GeForce or Quadro GPUs. It will only support Tesla GPUs (as described by this chart).
Now, I am going to assume that you are looking for this for professional use (as a server for a company, not home use for gaming or something else). If you are looking for something with 6 GPUs because you need that much power, check out the Nvidia VCA. It holds 8 Nvidia Quadro GPUs and features 20 physical Intel Xeon cores, and 256 GB of RAM. While it does not include internal storage beyond a 2 TB SSD, if you are dropping the money on that beast, buying a large NAS and the 10GBps network infrastructure equipment you will want to connect all these toys won't seem expensive.