I take it you mean while Titanic was still afloat?
In which case not a lot. The days of mobile pumps and damage control teams were a long way off and mostly confined to Navies and the influx of water into her hull was too great for any amount of help.
If you mean after Titanic had sunk ?What else could have assisting ships done besides pick up the survivors in the lifeboats ?
I think Mersey ignored the question when he said ''Many , if not all , could have been saved if Californian had answered Titanic's distress and had come immediately to their assistance." (If not correct, something on the order of that quote.)Personally, it's my opinion that John's question (above) hits the nail on he thumb. It's the "Ouchy" question that was avoided at all costs in 1912 and has continued to be ignored. Was there more that could have been done? Perhaps Titanic was lost, but would it have been possible with the knowledge and equipment aboard to have prolonged the life of the ship?
Even so, the kind of damage control which can be applied in even nondescript small vessels today far exceeds the knowledge and equipment available to Chief Engineer Bell and his men.
-- David G. Brown