Read what he said, he never said Mourinho hasn't spent absurd amounts. It's that Pep has managed to outspend him despite having a far more stacked squad when he took over. Compared to every club bar one in PL he is doing fine, and that club happens to have the manager at the helm who has added to what was an already stacked squad.
We are the underdogs in this race and it'll remain that way if it does go down to the wire, Pep already had set of world class players in KDB, Silva and Aguero when he arrived. Players who have spent multiple seasons at the club and been part of multiple title wins (Silva and Aguero). How many we had apart from DDG? Mourinho has had to rebuild the attack from ground up and it shouldn't be a surprise to many that we are struggling without key personnel. Job here is more difficult than one at City, there were defensive frailties in City squad and he managed to fix that in this window. Since July they have been favorite for PL title.
Look at our team when he took over and he has to build basically a new defence along with new midfield and new attack. Still there are lots of holes in the squad, we don't have a specialist full back or a winger. Our squad options when our key men are out injured are Lingard and Young. Pep can throw on Bernardo Silva or Sterling or Danilo if required.
Manchester City added Sterling and KDB to what was an already devastating attack with Aguero and Silva, they were favorites for title that season and their form completely fell off the cliff when KDB picked up an knee injury and they announced arrival of Pep in early January.
Again you are missing the point, players take time to bed in and get used to. Look at the set of attackers he is using this season, with the exception of Bernardo Silva (who he is slowly easing in) rest have been there for at least a season and therefore you can see the chemistry in their play.