There is no limit on the max no. of fields, but defining such a large no. of fields will make u worry to handle. So instead of doing this, better u should narrow your requirements, try to remove redundancy, and the most important thing in filemaker is to relate things properly. Making use of these things will result an effecient and portable database.
Actually there is no limit for this.
But keep in mind that if u hv requirments for more no of fields,1st try to split these table by Normalisation Concept(for more go through googles).Then you make relationship among these table and procede...................