Well, as usual, Trump made several statements leaning one way or another.
There is also the disturbing coincidence of organising a protest near the Capitol and an attempt to overturn the results of elections, using fake electors, etc... as found out by the committee.
Finally, on the Capitol events themselves, even if his statements did not explicitly called for storming the Capitol, there may be other charges. The accusation may not be sedition, but failure to act. He did not ask rioters to stop from the start of the assault. Trump waited 2 hours after the assault before telling rioters to leave. There is now an accumulation of evidence (emails, phone data, testimonies) about what Trump did and said during the riot. If the testimonies, and other evidence which are going to be presented, can show that he knew what was happening and failed his presidential duty to protect the constitution, it can be a clear case of failure to act in order to stop the riot, or even of complicity.