Can this ITX case support a full-length graphics card, and if so, what is the maximum length allowed?

Yes, this ITX case supports cards up to 13 inches (330mm), which allows for most high-end GPUs.

Questions & Answers: SilverStone Technology SST-FTZ01B-E Aluminum Unibody ITX Small Form Factor Computer Case with PCI-E Riser and ATX PSU Support Black

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SilverStone Technology SST-FTZ01B-E Aluminum Unibody ITX Small Form Factor Computer Case with PCI-E Riser and ATX PSU Support Black

Classic exterior built from aluminum unibody frame. Fits in nearly any environment with horizontal or vertical orientation
Support cards up to 13 inches (330mm) to fit most high-end GPUs for compute power far exceeding consoles
Mini-ITX motherboard & ATX PSU compatible for wide array of building possibilities
Maximum performance in slim form factor with support for AIO liquid cooling
Positive air pressure design for excellent cooling/quietness and dust-prevention