The multiplier used by Finance for this type of tax reduction is about 0.2 over the short term and 0.6 over the long term. Compared with other multipliers, it's relatively smaller. The net amount of benefits, which is about $1.4 billion, provided through that tax cut using that multiplier would not, I think, lead to a very significant proportion of GDP. It would probably be rounded to almost zero. That's all I can tell you.
On April 12th, 2016. See this statement in context.