how to gain many tc in one day?

well u could join the tourney,some events,or sell something.......

Buy cheap items on the forum and resell them on the market for a higher price

Is there any betting in Toribash? How about paypal?

Betting with paypal?
This would get a large amount of Paypal fraud.

There is a betting function ingame and often betting rooms are made. TC can be bought with paypal from certain people such as 'Missuse'.

Irookie and some others are selling too
What you can do too is
Make art and sel it

Try watching tutorials about Photoshop or GIMP. Make art, sell it, bet and join events. Good luck.

what kind of art that can be sell?

Heads,Textures,Trails,Grounds,etc