Hi
Welcome to INTEL forum. The "Arria 10 SOC FPGA Development Kit" eval boards is meant for evaluation study purpose only and not to be used as end final product.
• https://www.intel.com/content/dam/altera-www/global/en_US/support/boards-kits/arria10/soc/Production_files/arria-10-soc-dev-kit-quick-start-guide.pdf
• Refer to end of page 3 disclaimer section
We only have MTBF for Arria 10 FPGA device itself but not for dev kit board. If you are interested of the Arria 10 FPGA device MTBF data, please post new forum thread to ask for it. Thanks