I expect the cables will be quite fat (physically) which reduces their resistance. Also, by increasing the voltage, you decrease the current for any given power, which decreases the resistive losses. So yes, there will be some losses in transmission (as is the case for literally all power transmission methods), but engineers clearly consider this and design around it.
HVDC cables are very efficient physically. Haven't dived into this cable's details yet, but you can push 1.5GW over two conductors roughly 5" in diameter each.
