See below.  My back of the envelope math is that there could be about $600B of PPP demand if every eligible business applied for the maximum amount, so the $349B would be just under 60% of that amount. 

I suspect that this tweet is intended to slow down the tsunami of applications that is coming on Monday.  I will go on record as predicting that this won’t prevent Monday from being utter chaos for banks and applicants.  Bold, I know.  

Donald J. Trump ⁦‪@realDonaldTrump⁩ I will immediately ask Congress for more money to support small businesses under the #PPPloan if the allocated money runs out. So far, way ahead of schedule. ⁦‪@BankofAmerica⁩ & community banks are rocking! ⁦‪@SBAgov⁩ ⁦‪@USTreasury⁩   4/4/20, 11:09 AM