Some of these may be obvious and important, such as gaps around pipes or cables that move through exterior walls. Filling these is easy and addresses what may be a large gap on a side wall. Gaps around doors and windows also could be filled in, and all of this also leads to better containment of heat or cooling to maintain the indoor temperature where wanted. There may be some very difficult ant pests, such as the white footed ant, where insecticides are not going to be the total answer, and sealing outside openings helps a great deal. This might include running a line of caulk along the underside of siding to close off those major gaps - once sealed properly the ants have to look somewhere else for entry. 

Trying to seal up gaps on the interior is going to be less likely to succeed, as there are just so many potential places ants could move into the home from wall voids or under floors or down from attics. But, the combination of cleanup and sanitation outdoors to remove ant harborage, keeping shrubs and trees from touching the structure and creating ant highways, moisture management outdoors, removal of food resources indoors, exclusion to eliminate entry points, and the use of contact insecticides and baits gives the best chance to win the battle.