How long UE will decode PCFICH?

PCFICH will indicate PDCCH symbols.
How long UE will decode PCFICH, every TTI or subframe, or frame or something else?

PCFICH is carried in every subframe and the mapping to resource grid is a function of physical cell id and system bandwidth. Without decoding PCFICH, UE cant know how many symbols PDCCH spanned across. So, UE attempts to decode it every subframe.