The 18-year-old is yet to make his senior debut for the Reds but was included in their squad for last season’s UEFA Europa League clash with FC Porto.
Blake will be available for Saturday’s FA Cup third qualifying round tie against Cirencester Town.
His arrival follows Dominic Johnson-Fisher’s departure from Truro to join National League side Worthing last week.
"Zyan has a lot of ability and can go past a player," manager John Askey told the club website.
"He is quick, has a good shot on him, and has scored goals at youth and under-21 level.
"He can be a good impact player for us and if he does well, he will be looking to start games.
"This signing shows we are moving forward because if a club like Nottingham Forest allows players to come to us, it's because they know the lad is going to get treated properly."