Answer from Ann Harrison
Firebird tables are limited by a factor related to the record data size. A table will hold approximately 2,700,000,000 10 byte records, or 1,000,000,000 50 byte records or 620,000,000 100 byte records. Firebird 2 removes this restriction.
The file size is limited by the operating system and a database can consist of several files.
A single record can not exceed 64Kb, excluding blob data.