From generic_mod_demod.py, here is how the taps are generated. The taps are then used by a polyphase filterbank-based arbitrary resampler. I think the answer to your question is 11.
nfilts = 32
ntaps_per_filt = 11
ntaps = nfilts * ntaps_per_filt * int(self._samples_per_symbol) # make nfilts filters of ntaps each
self.rrc_taps = filter.firdes.root_raised_cosine(
nfilts, # gain
nfilts, # sampling rate based on 32 filters in resampler
1.0, # symbol rate
self._excess_bw, # excess bandwidth (roll-off factor)
ntaps)
self.rrc_filter = filter.pfb_arb_resampler_ccf(self._samples_per_symbol,
self.rrc_taps)