I can think of a lot more substantial measures that could help more than praying. A disaster of this magnitude needs boots on the ground, helicopters, medical supplies, food, and water. Quebec offered supplies and the Texas Secretary of State declined the offer and said, “just send prayers.” Trump is apparently back in Texas too in hopes of erasing his first appearance when he talked about ratings and the crowd size. I really think this disaster might be bigger than Katrina. Houston is the fourth largest city in the United States. I drove through it once and it took almost two hours. It’s a big, sprawled out place and judging from all the images and video I’ve seen, I think it probably will be the costliest hurricane ever or among the costliest ever. It impacted fuel prices almost immediately and the refineries I saw on video were still partially submerged.
Here’s a political cartoon I came across that’s pretty good. 
If you want to donate some money, I suggest the Foundation Beyond Belief. There’s no religious message attached to your donation with them. They have a disaster relief tab on their website.
Dispatches from a lowly biologist. 