Increasing the block size isn't going to matter much because they aren't even using the current capacity.
BTC avg block size = 629KB
BCH = 56KB
At least according to https://bitinfocharts.com
If BCH isn't using anything near their current capacity how would increasing the block size have any effect? Over the long term, maybe, but by then BTC will have worked out the kinks in the Lightening Network.
BCH has to do a better job of convincing people to use their network before it stands a chance of toppling BTC.
RE: BITCOIN CASH IS MOVING TO BIGGER BLOCKS AS OF MAY 15, 2018.