i tried wit this code
echo 'Yes newsletter enable';
Looking for other solution if exist somthing like Mage::getStoreConfig .....
The method isNewsletterEnabled, doesn't exists in all blocks, only in two as far as I can see doing a quick search of the core:
Meaning that you can't just call it from any template file, either you can extend your block from these, or you can use the following code to replicate it:
Hope this helps :-)