I don't think so, but you can do the saccharification alone in same conditions, just without the yeast, to compare; probably it is not exactly the same but maybe it is quite close.  

I don't think it is possible

There is an excellent article published 30 years ago where you can find the answer:

Good luck!

http://www.cert.ucr.edu/research/ses/wymanpublications/SSF%20of%20lignocellulose-%20process%20evaluation.pdf

Yes. Using mass balance: input=output

Thank you Professor Nikolay Vassilev, the paper is really educative. Muchas gracias, Fue muy útil

Yes, you can know arbitarily how much sugar has been produced by the enzymatic hydrolysis and amount of sugar being consumed by yeast. IN that case you need to do the complete material balance. You should conduct the biomass composition analysis  both at the start of the expt and at the end of the experiment. The composition analysis would tell you that what was the initial and final cellulose and xylan content in the biomass. The ethanol yield would tell you that how much glucose in form of cellulose was fermented and rest remaining was used by yeast during growth and fermentation. But you have to be very cautious while measuring the weight (both wet and dry) and also the volumes (saccharified broth/fermentation broth). The handling losses should be minimal to get a more accurate result. Hope it could help you in designing your experiment