I don't think they will know very much until after the bid expires. GE may be negotiating with/talking to certain major holders and get a rough indication, however, they cannot make any binding agreements unless they are made public.
For example AP1 with their 9% could change their mind and pull out from their accept.
Another example, Nordnet (a Swedish internet bank) now collects withdrawals that they will "deliver" mid next week. I guess most banks and brokers collect both withdrawals and accepts and report them at the end of the tender period. With my Swedish bank/broker Avanza I can, if I would have accepted, withdraw electronically till the last minute of the tender period.