Is there a discount provided for public transport in SIN for senior citizens?

If so, does it also apply to foreigners that are visiting!

Thanks!

No. Only Singapore residents get the card as specified on the SMRT website:
http://www.smrt.com.sg/trains/trains_fares.html

Singapore citizens and permanent residents aged 60 years and above and using the Senior Citizen ez-link cards are eligible for travel concession.

The fares are so cheap anyway. So honestly there is not that much savings.

You won't have to pay more than US$1.25 for the max distance on the subway (MRT) or US0.80 on the buses.

You can get a stored value card (called EZ LINK) at MRT stations.

More info here: http://www.visitsingapore.com/publish/stbportal/en/home/getting_around/transportation/mrt.html