For the T4FHSA, Box 18 and 30 supposed to match, correct? Example I contributed $8000 this year for Box 18, does that mean the tax deductible for box is also $8000?

No. On the T4FHSA, Box 18 is for Contributions. Box 30 is for income tax deducted. You will only have something in Box 30 if you took out money from your FHSA and taxes were deducted.